Genealogy
Genealogy (from Greek: , genea, "family"; and , logos, "knowledge") is the study and tracing of families. Modern genealogical research is a complex process that involves more than affixing a collection of names to a pedigree chart. Rather, genealogy involves identifying ancestral or descendant families by using historical records to establish biological, genetic, or familial kinship. Reliable conclusions are based on the quality of sources (ideally original records, rather than derivatives), the information within those sources (ideally primary or firsthand information, rather than secondary or secondhand information), and the evidence that can be drawn (directly or indirectly) from that information. In many instances, genealogists must skillfully assemble indirect or circumstantial evidence to build a case for identity and kinship. All evidence and conclusions, together with the documentation that supports them, is then assembled to create a cohesive "genealogy" or "family history."  Traditionalists may differentiate between these last two terms, using the former to describe skeletal accounts of kinship (aka family trees) and the latter as a "fleshing out" of lives and personal histories. However, historical, social, and family context is in any case essential to achieving correct identification of individuals and relationships.

# Overview
In its original form, genealogy was mainly concerned with the kinship and descent of rulers and nobles, often arguing or demonstrating the legitimacy of claims to wealth and power. The term often overlapped with heraldry, in which the ancestry of royalty was reflected in their coats of arms. Many claimed ancestries have been considered fabrications by modern scholars. An example of this puffery would be the Anglo-Saxon chroniclers who traced the ancestry of several English kings back to the god Woden, the English version of the Norse god Odin. This mythological origin of English kings is related in a number of derivative sources, such as The Scyldings, wherein the Anglo-Saxon Chronicle is cited as a primary source. The following passage appears in the entry for A.D. 449: "Their leaders were two brothers, Hengest and Horsa; who were the sons of Wihtgils; Wihtgils was the son of Witta, Witta of Wecta, Wecta of Woden. From this Woden arose all our royal kindred, and that of the Southumbrians also." In this context "royal kindred" refers to English kings. If these descents were true, Queen Elizabeth II would be a descendant of Woden, via the kings of Wessex.
In modern times, genealogy became more widespread, with commoners as well as nobility researching and maintaining their family trees. Genealogy received a boost in the late 1970s with the premiere of the television adaptation of Alex Haley's fictionalized account of his family line, Roots: The Saga of an American Family, leading to genealogy becoming popular hobby. With the advent of the Internet, the number of resources available to genealogists has vastly increased, resulting in an explosion of interest in the topic. According to some sources, genealogy is one of the most popular topics on the Internet.
Genealogists who are hobbyists typically pursue their own ancestry.  Professional genealogists may conduct research for others, publish books on genealogical methods, teach, or work for companies that provide online databases. Both also try to understand not just where and when people lived, but also their lifestyles, biographies, and motivations. This often requires  or leads to  knowledge of antiquated laws, old political boundaries, migration trends, and historical social conditions.
Genealogists and family historians often join family history societies where novices can learn from more experienced researchers, indexing projects make records more accessible, and efforts to preserve historical records may be undertaken.  The Internet has also become a major source of data, education, and communication for genealogists.
Genealogists sometimes specialize in a particular group, e.g. a Scottish clan; a particular surname, such as in a one-name study; a small community, e.g. a single village or parish, such as in a one-place study; or a particular, often famous, person.

# The Genealogical Research Process
Genealogists begin their research by collecting family documents and stories.  This creates a foundation for documentary research, which involves examining and evaluating historical records for evidence about ancestors and other relatives, their kinship ties, and the events that occurred in their lives.

## Genetic analysis
With the discovery that a person's DNA contains information that has been passed down relatively unchanged from early ancestors, analysis of DNA has begun to be used for genealogical research. There are two DNA types of particular interest. One is the mitochondrial DNA which we all possess and which is passed down with only minor mutations through the female line. The other is the Y-chromosome, present only in males, which is passed down with only minor mutations through the male line.
A genealogical DNA test allows two individuals to estimate the probability that they are, or are not, related within a certain time frame. Individual genetic test results are being collected in various databases to match people descended from a relatively recent common ancestor.  See, for example, the Molecular Genealogy Research Project. These tests are limited to either the direct male or the direct female line.
On a much longer time scale, genetic methods are being used to trace human migratory patterns and to determine biogeographical and ethnic origin. As this research is unable to identify individuals, families, and specific relationships, most of it is of only tangential interest to genealogists.

## Sharing data among researchers
Data sharing among genealogical researchers has grown to be a major use of the Internet. Most genealogy software programs can export information about persons and their relationships in GEDCOM format, so it can be shared with other genealogists by e-mail and Internet forums, added to an online database such as GeneaNet, or converted into a family web site using online genealogical tools such as PhpGedView. Many genealogical software applications also facilitate the sharing of information on CD-ROMs and DVDs made on personal computers.
One phenomenon over the last few years has been that of large online genealogical databases attracting such large flash crowds that the database's host server collapses, causing service to be suspended while upgrades are made to accommodate the traffic load. This happened with FamilySearch, the Commonwealth War Graves Commission's database of war graves, and in January 2002 with the much-anticipated British census for 1901.

## Volunteerism
Volunteer efforts figure prominently in genealogy. These efforts range from the extremely informal to the highly organized.
On the informal side are the many popular and useful message boards and mailing lists regarding particular surnames, regions, and other topics. These forums can be used to try to find relatives, request record lookups, obtain research advice, and much more.
Many genealogists participate in loosely organized projects, both online and off. These collaborations take numerous forms, of which only a few are mentioned here. Some projects prepare name indexes for records, such as probate cases, and either publish the indexes or place them online. These indexes can be used as finding aids to locate original records. Other projects transcribe or abstract records, which is especially helpful for searching records by something other than surname. For example, a genealogist using the cluster genealogy research technique might want to search records by land description. For this reason, deeds are a good candidate for transcription. Offering record lookups is another common service, and projects are usually organized by geographic area. Volunteers such as those involved in RAOGK offer to do record lookups in their home areas for researchers who are unable to travel.
Those looking for a structured volunteer environment can join one of thousands of genealogical societies worldwide. Like online forums, most societies have a unique area of focus such as a particular surname, ethnicity, geographic area, or descendency from participants in a given historical event. These societies are almost exclusively staffed by volunteers and may offer a broad range of services. It is common for genealogical societies to maintain libraries for members' use, publish newsletters, provide research assistance to the public, offer classes or seminars, and organize efforts such as cemetery transcribing projects.

# Records in genealogical research
To keep track of their citizens, governments began keeping records of persons who were neither royalty nor nobility. In much of Europe, for example, such record keeping started in the 16th century. As more of the population was recorded, there were sufficient records to follow a family.
Major life events were often documented with a license, permit, or report that was stored at a local, regional or national office or archive. Genealogists locate these records and extract information to discover family relationships and recreate timelines of persons' lives.
In China and other Asian countries, genealogy books are used to record the names, occupations, and other vitals of family members with some have dating back hundreds or even thousands of years. In the eastern Indian state of Bihar, there is a written tradition of genealogical records among Maithil Brahmins and Karna Kayasthas called "Panjis", dating to the 12th century CE, and are consulted prior to marriages even today.
In Ireland, genealogical records were recorded by professional families of senchaidh (historians). This continued until as late as the mid-17th century, when Gaelic civilization died out. Perhaps the most outstanding example of this genre is Leabhar na nGenealach/The Great Book of Irish Genealogies, by Dubhaltach MacFhirbhisigh (d. 1671), which was published in 2004.
Records that are used in genealogy research include:
- Vital records
Birth records
Death records
Marriage and divorce records
- Birth records
- Death records
- Marriage and divorce records
- Adoption records
- Biographies and biographical profiles (e.g. Who's Who)
- Census records
- Church records
Baptism or christening
Confirmation
Bar or bat mitzvah
Marriage
Funeral or death
Membership
- Baptism or christening
- Confirmation
- Bar or bat mitzvah
- Marriage
- Funeral or death
- Membership
- City directories and telephone directories
- Coroner's reports
- Court records
Criminal records
Civil records
- Criminal records
- Civil records
- Diaries, personal letters and family Bibles
- Emigration, immigration and naturalization records
- Hereditary & lineage organization records, e.g. Daughters of the American Revolution records
- Land and property records, deeds
- Medical records
- Military and conscription records
- Newspaper articles
- Obituaries
- Occupational records
- Oral histories
- Passports
- Photographs
- Poorhouse, workhouse, almshouse, and asylum records
- School and alumni association records
- Ship passenger lists
- Social Security (within the USA) and pension records
- Tax records
- Tombstones, cemetery records, and funeral home records
- Voter registration records
- Wills and probate records
As a rule, genealogists begin with the present and work backward in time. Written records have the property of hindsight in that they only tell where a person might have lived and who their parents were, not where they and their descendants might subsequently reside. Two exceptions are when genealogists interview living relatives as to who and where their children and grandchildren are, or try to locate relatives who may already have traced their families back to an ancestor they have in common.

## LDS collections
The Church of Jesus Christ of Latter-day Saints (LDS) has engaged in large-scale microfilming of available records of genealogical value. It has also compiled indexes of the submissions of its members. This has resulted in several major databases: the International Genealogical Index, or IGI, which includes both data extracted from filmed civil and ecclesiastic records from various worldwide locales and member-submitted information; the Ancestral File, or AF, which includes the contributions of church members; and the Pedigree Resource File, or PRF, compiled from member and non-member submissions. The IGI contains hundreds of millions of records of individuals who lived between 1500 and 1900, primarily in the United States, Canada and Europe. The AF and PRF often contain numerous duplications of IGI records.
The LDS Family History Library in Salt Lake City, Utah, houses microfilm and microfiche copies in over 4,000 "Family History Centers" worldwide available for on-site research. Most of these same resources are also available on ther FamilySearch Internet website providing free access to the International Genealogical Index, the Ancestral File, the Pedigree Resource File, 1880 United States federal census index, an 1881 British census index, an 1881 Canadian census index, the U.S. Social Security Death Index, research guides, and genealogical word lists.

# Types of genealogical information
The classes of information that genealogists seek include: place names, occupations, family names, first names, and dates. Genealogists need to understand such items in their historical context in order to properly evaluate genealogical sources.

## Place names
While the locations of ancestors' residences and life events are core elements of the genealogist's quest, they can often be confusing. Place names may be subject to variant spellings by partially literate scribes. Locations may have identical or very similar names. For example, the village name Brocton occurs six times in the border area between the English counties of Shropshire and Staffordshire. Shifts in political borders must also be understood. Parish, county and national borders have frequently been modified, with outlying and detached areas being reassigned. Old records may contain references to farms and villages that have ceased to exist because of disease, famine or wars.
Available sources may include vital records (civil or church registration), censuses, and tax assessments. Oral tradition is also an important source, although it must be used with caution. When no source information is available for a location, circumstantial evidence may provide a probable answer based on a person's or a family's place of residence at the time of the event.
Maps and gazetteers are important sources for understanding the places researched.  They show the relationship of the area to neighboring communities and may help in understanding migration patterns.

## Occupations
Occupational information may be important to understanding an ancestors life and for distinguishing two people with the same name. A persons occupation may have been related to his or her social status, political interest, and migration pattern. Since skilled trades are often passed from father to son, occupation may also be indirect evidence of a family relationship.
It is important to remember that occupations sometimes changed or may be easily misunderstood. Workmen no longer fit for their primary trade often took less prestigious jobs later in life. Many unskilled ancestors had a variety of jobs depending on the season and local trade requirements. Census returns may contain some embellishment; e.g., from Labourer to Mason, or from journeyman to Master craftsman. Names for old or unfamiliar local occupations may cause confusion if poorly legible. For example, an ostler (a keeper of horses) and a hostler (an innkeeper) could easily be confused for one another. Likewise, descriptions of such occupations may also be problematic. The perplexing description "ironer of rabbit burrows" may turn out to describe an ironer (profession) in the Bristol district named Rabbit Burrows. Several trades have regionally preferred terms. For example, shoemaker and cordwainer have the same meaning. Finally, many apparently obscure jobs are part of a larger trade community, such as watchmaking, framework knitting or gunmaking.
Occupational data may be reported in occupational licenses, tax assessments, membership records of professional organizations, trade directories, census returns, and vital records (civil registration). Occupational dictionaries are available to explain many obscure and archaic trades.

## Family names
Family names are simultaneously one of the most important pieces of genealogical information, and a source of significant confusion for researchers.
In many cultures, the name of a person references the family to which he or she belongs. This is called the family name, or surname. It is often also called the last name because, for most speakers of English, the family name comes after the given name (or names). However, this is not the case in other cultures, e.g., Chinese family names precede the given name.
Patronymics are names that allow identification of an individual based on the father's name, e.g., Marga Olafsdottir or Olaf Thorsson. Many cultures used patronymics before surnames were adopted or came into use. The Dutch in New York, for example, used the patronymic system of names until 1687 when the advent of English rule mandated surname usage. In Iceland, patronymics are used by a majority of the population; surnames made their way into the language in the 19th and 20th century, but are not widely used. In order to protect the patronymics system, it is forbidden by law to introduce a new surname in Iceland. In Norway patronymics were generally in use through the 1800s and beyond, though surnames began to come into fashion toward the end of that century in some parts of the country.  Not until 1923 was there a law requiring surnames.
The transmission of names across generations, marriages and other relationships, and immigrations also causes significant inaccuracy in genealogical data. For instance, children may sometimes take or be given step-parent, foster parent, or adoptive parent names. Women in many cultures have routinely used their spouse's surnames. When a woman remarried, she may have changed her name and the names of her children; only her name; or changed no names. Her birth name (maiden name) may be reflected in her children's middle names; her own middle name; or dropped entirely.
Official records do not capture many kinds of surname changes. For example, fostering, common-law marriage, love affairs, changes in career or location may all result in name changes which are not reflected as such in official records.
Surname data may be found in trade directories, census returns, birth, death, and marriage records.

## Given names
Genealogical data regarding given names (first names) is subject to many of the same problems as are family names and place names.
Additionally, nicknames for personal names are very common  Beth, Lizzie or Betty are common for Elizabeth, which can be confused with Eliza. Patty has been used as a diminutive form for Martha. Also, Amy used for Alice, and Nancy/Ann, and Polly used for a number of feminine names including Mary Ann and Elizabeth. Peggy is often used as a nickname for Margaret. While the feminine names are the most confusing, masculine names can also interchange: Jack, John & Jonathan, Joseph & Josiah, Edward & Edwin, etc.
Middle names provide additional information. Middle names may be inherited, or follow naming customs. Middle names may sometimes be treated as part of the family name. For instance, in some Latin cultures, both the mother's family name and the father's family name are used by the children. Official records may record full names in a variety of ways: First, Middle, Last; Last, Middle, First; Last, First Middle; Last, First, M.
Historically, naming traditions existed in some places, where the names given to one's children were sometimes influenced by a particular formula. It is important to recognize, however, that naming traditions were not used in all families and did not always follow the same formula. They are just a pattern of naming that was common in a particular area during a particular time.
An example is Scotland and Ireland, where:
- 1st son - named after paternal grandfather
- 2nd son - named after maternal grandfather
- 3rd son - named after father
- 4th son - named after father's oldest brother
- 1st daughter - named after maternal grandmother
- 2nd daughter - named after paternal grandmother
- 3rd daughter - named after mother
- 4th daughter - named after mother's oldest sister
Another example is in some areas of Germany, where siblings were given the same first name, often of a favourite saint or local nobility, but different second names and known by their second names (Rufname).
If a child died, the next child of the same gender that was born may have been given the same name. It is not uncommon that a list of a particular couple's children will show one or two names repeated. Although this can be confusing, it can also assist a researcher in discovering the date of death for the previous siblings of the same name.
Personal names go through periods of popularity, so it is not uncommon to find many similarly-named people in a generation, and even similarly-named families; e.g., "William and Mary and their children David, Mary, and John".
Many names may be identified strongly with a particular gender; e.g., William for boys, and Mary for girls. Other names may be ambiguous, e.g., Lee, or have only slightly variant spellings based on gender, e.g., Frances (usually female) and Francis (usually male).

## Dates
It is wise to exercise extreme caution and skepticism with information about dates. Dates are more difficult to recall years after an event, and are more easily mistranscribed than other types of genealogical data. Therefore, one should evaluate whether the date was recorded at the time of the event or at a later date. Dates of birth in vital records or civil registrations and in church records at baptism are generally accurate because they were usually recorded near the time of the event. Family Bibles are often a reliable source for dates, but can be written from memory long after the event. When the same ink and handwriting is used for all entries, the dates were probably written at the same time and therefore will be less reliable since the earlier dates, at least, were probably recorded well after the event. The publication date of the Bible also provides a clue about when the dates were recorded since they could not have been recorded at any earlier date.
People sometimes reduce their age on marriage, and perhaps those under "full age" may increase their age in order to marry or to join the armed forces. Census returns are notoriously unreliable for ages or for assuming an approximate death date. The 1841 census in the UK is rounded down to the next lower multiple of five years. Also, caution should be used when estimating a date for a husband's death based on his absence from the census. A woman at home while her husband is away could be identified as head of household or assumed to be a widow.
Baptismal dates are often used to approximate birth dates; however, some families wait 3-5 years before baptizing children, and adult baptisms are not unknown. In addition, both birth and marriage dates may have been adjusted to cover for pre-wedding pregnancies. It is very common for the first child to be born before or within a few months of a marriage and sometimes baptized in the mother's name, later adopting the father's name after the parents' marriage. The father's name can be used even if no marriage has occurred.
Calendar changes must also be considered.  In 1752 the date of the new year was changed in England and her American Colonies. Before 1752 the new year started on the 25 March, but in 1752 this was changed to the 1 January. England also made the transition to the Gregorian calendar from the Julian calendar in 1752, several months later, and it is all too easy for some genealogists to assume that these separate changes belong together. Many other European countries had already made the changes, sometimes many decades apart, and by 1751 there was an 11 day discrepancy between the date in England and the date in other European countries. The date continued to be recorded as usual in 1752 until 2 September 1752, the following day became 14 September 1752. Dates that were recorded in the older system can be shown by "double dating". For example:
Original date: 24th of March 1750; Modern date: 24 March 1751; Double dating: 24 March 1750/51.
A concrete example illustrates the possibilities for confusion. In the year 1715:
- France used the Gregorian calendar with the year starting on 01 January
- England used the Julian calendar and the year started on 25 March.
- In England, 1700 had been a leap year; in France it had not.
- 10 June 1715 in England appears to be eleven days "earlier" than the same day, 21 June 1715, in France.
- England kept the same year going until far into March, so 15 February 1715 in England was 26 February 1716 in France.
- In Scotland, still using the Julian calendar, the same day was 15 February 1716
For events occurring before 1752 in countries where the Julian calendar was still in use, it is best to use double dating whenever the exact year can be ascertained. When transcribing an original record where the exact year is evident but not expressed, the double date can be written as, for example, "24 March 1750".
One should also be aware that, in those places using the old Julian calendar, the numbering of months also varied. The "1st month" of the year was considered March, the second April, the third May, and so on. Those 24 days in March which fell before the beginning of the year were generally regarded as being part of the first month.
NOTE:
The foregoing may be true for British genealogical records but does in no way apply to records in other countries. A notable exception is the Nordic countries, especially Sweden, which have very detailed and mostly accurate records in the form of church records from the 18th century onwards.  But there, as in any historical research, a critical review of all information and an assessment of the reliability of each source is required.

# Reliability of sources
Information found in historical or genealogical sources can be unreliable and it is good practice to evaluate all sources with a critical eye. Factors influencing the reliability of genealogical information include:   the knowledge of the informant (or writer); the bias and mental state of the informant (or writer); the passage of time and the potential for copying and compiling errors.

## Knowledge of the informant
The informant is the individual who provided the recorded information. Genealogists must carefully consider who provided the information and what he or she knew. In many cases the informant is identified in the record itself. For example, a death certificate usually has two informants: a physician who provides information about the time and cause of death and a family member who provides the birth date, names of parents etc.
When the informant is not identified, one can sometimes deduce information about the identity of the person by careful examination of the source. One should first consider who was alive (and nearby) when the record was created. When the informant is also the person recording the information, the handwriting can be compared to other handwriting samples.
When a source does not provide clues about the informant, genealogists should treat the source with caution. These sources can be useful if they can be compared with independent sources. For example, a census record by itself cannot be given much weight because the informant is unknown. However, when censuses for several years concur on a piece of information that would not likely be guessed by a neighbor, it is likely that the information in these censuses was provided by a family member or other informed person. On the other hand, information in a single census cannot be confirmed by information in an undocumented compiled genealogy since the genealogy may have used the census record as its source and might therefore be dependent on the same misinformed individual.

## Bias and mental state of the informant
Even individuals who had knowledge of the fact, sometimes intentionally or unintentionally provided false or misleading information. A person may have lied in order to obtain a government benefit (such as a military pension), avoid taxation, or cover up an embarrassing situation (such as the existence of a non-marital child). A person with a distressed state of mind may not be able to accurately recall information. Many genealogical records were recorded at the time of a loved one's death, and so genealogists should consider the effect that grief may have had on the informant of these records.

## The effect of time
The passage of time often affects a person's ability to recall information. Therefore, as a general rule, data recorded soon after the event is usually more reliable than data recorded many years later. However, different types of data are more difficult to recall after many years than others. A data type especially prone to recollection errors is dates. Also the ability to recall is affected by the significance that the event had to the individual. These values may have been affected by cultural or individual preferences.

## Copying and compiling errors
Genealogists must consider the effects that copying and compiling errors may have had on the information in a source. For this purpose, sources are generally categorized in two categories: original and derivative. A derivative source is information taken from another source. An original is one that is not based on another source. Each time a source is copied, information about the record may be lost and errors may creep in from the copyist misreading, mistyping, or miswriting the information. Genealogists should consider the number of times information has been copied and the types of derivation a piece of information has undergone. The types of derivatives include: photocopies, transcriptions, abstracts, translations, extractions, and compilations.
In addition to copying errors, compiled sources (such as published genealogies and online pedigree databases) are susceptible to misidentification errors and incorrect conclusions based on circumstantial evidence. Identity errors usually occur when two or more individuals are assumed to be the same person. Circumstantial or indirect is evidence that does not explicitly answer a genealogical question, but either may be used with other sources to answer the question, suggest a probable answer, or eliminate certain possibilities. Compiled sources sometimes draw hasty conclusions from circumstantial evidence without sufficiently examining all available sources, without properly understanding the evidence, and without appropriately indicating the level of uncertainty.

# The "maximum relationship"
One of the interests in the field of biology in which some genealogists share an interest is in determining the maximum degree of separation that currently exists among all people in the world, that is to say, how many generations back is the most recent common ancestor that the two most distantly related people on earth share.
Latest models, taking into account sexual differentiation, monogamy and realistic migration patterns suggest that the most recent common ancestor (MRCA) of all humans probably lived 75-150 generations or 2,000-4,000 years ago. Moreover, according to these models, the MRCA is likely to have lived somewhere in Southeast Asia (increasing the likelihood of his or her descendants reaching the remote islands of the Pacific), is equally likely to be a man or woman, and is not characterized by an unusually large number of children. These models also show that while a large group (indeed all humans) share recent common ancestors, a given person is likely to share the vast majority of his or her genes with a very small local group.

# Software
Genealogy software is computer software used to collect, store, sort, and display genealogical data. At a minimum, genealogy software tends to accommodate basic information about individuals, including births, marriages, and deaths. Many programs allow for additional biographical information, including occupation, residence and notes. Many genealogy programs also offer an easy method for keeping track of the sources for each fact.
Certain programs are geared toward specific religions, and include additional fields relevant to that religion. Other programs focus on certain geographical regions.
Some programs allow for the import of digital photographs, and sound files. Other programs focus on the ability to generate kinship charts, family history books and other publications. Some programs are more flexible than others in allowing for the input of same sex marriages and children born out of wedlock.
A move is on to incorporate fields for the input of genealogical DNA test results, though this information can be added into the "Notes" field of almost all genealogy software.
Most genealogy software allow for the export of data in the GEDCOM format that can be shared with people using different genealogy software. Certain programs allow the user to restrict the information that is shared, usually by removing information about living people out of privacy concerns.