Doctorate
A doctorate is an academic degree that indicates a high, if not the highest, level of academic achievement. A terminal degree in most countries, some Central and Eastern European countries place the doctorate second only to the habilitation.
The term doctorate comes from the Latin docere, meaning "to teach", shortened from the full Latin title licentia docendi, meaning "license to teach." This was translated from the equivalent Arabic term ijazat attadris, which was a distinction granted to certain Islamic scholars, thus qualifying them to teach.

# Types of doctorate
Since the Middle Ages, there has been considerable evolution and proliferation in the number and types of doctorates awarded by universities throughout the world, and practices vary from one country to another. While a doctorate usually entitles one to be addressed as "doctor", usage of the title varies widely, depending on the type of doctorate earned and the doctor's occupation. See the main article for Doctor (title) for more information.
Broadly speaking, doctorates may be loosely classified into the following categories:

## Research doctorates
Research doctorates are awarded in recognition of both mastery of research methods (as evidenced in class grades and a comprehensive examination) and academic research that is ideally publishable in a peer-reviewed academic journal, but that will minimally be assessed by submission and defense of a thesis or dissertation.  The best-known degree of this type is that of Doctor of Philosophy (PhD) awarded throughout the world; others include the U.S. degrees of Doctor of Engineering (DEng) and Doctor of Science (DSc or ScD), the UK Engineering Doctorate (EngD), and the German degree of Doctor rerum naturalium (Dr.rer.nat.).
The minimum time required to earn a doctorate varies by country, and can be a short as three years (excluding bachelor's and master's studies). However, some candidates can take anywhere from five to ten years to complete. The median number of years to completion of doctoral degrees for all fields in the US is seven years. Students are discouraged from taking unnecessarily long to graduate by having their financial support (stipends, research funds, etc.) relinquished. Furthermore, doctoral applicants were previously required have a master's degree, but many programs will now accept students straight out of undergraduate studies.

## Higher doctorates
In some countries, especially the United Kingdom, Ireland and some Scandinavian, Commonwealth nations or former USSR countries, there is a higher tier of
research doctorates, awarded on the basis of a formally submitted portfolio of published research of a very high standard.  Examples include the Doctor of Science (DSc/ScD) and Doctor of Letters (DLitt/LittD) degrees found in the UK, Ireland and some Commonwealth countries, and the Danish doctorate (doktorgrad; e.g. dr.theol., doctor theologi, Latin for Doctor of Theology).
The German habilitation postdoctoral qualification is sometimes regarded as belonging to this category, even though, strictly speaking, the habilitation is not an academic degree, but rather a professional license to teach at a German university.
Higher doctorates are often also awarded honoris causa when a university wishes to formally recognize an individual's achievements and contributions to a particular field.

## Professional doctorates
Professional doctorates are awarded in certain fields where most holders of the degree are not engaged primarily in scholarly research, but rather in a profession, such as law, medicine, music or ministry.  Examples include the U.S. degrees of Doctor of Medicine (MD) and Doctor of Jurisprudence (JD), the Dutch Professional Doctorate in Engineering (PDEng), and the Czech degrees of Doctor of Dental Medicine (MDDr.) and Doctor of Veterinary Medicine (MVDr.).
The term Professional Doctorate is also used to refer to research doctorates with a focus on applied research. Among others, these include the Doctor of Education (EdD), Doctor of Applied Linguistics (DAppLing), and Doctor of Business Administration (DBA).

## Honorary doctorates
When a university wishes to formally recognize an individual's contributions to a particular field or philanthropic efforts, it may choose to a doctoral degree honoris causa (i.e., "for the sake of the honor"), the university waiving the usual formal requirements for bestowal of the degree. Some universities (e.g., Cornell University, the University of Virginia) do not award honorary degrees, feeling the bestowal unethical.

# Country-specific practice

## Argentina
Similar to other countries, in Argentina the doctorate (doctorado) is the highest. The intention is that candidates produce true and original contributions in a specific field of knowledge within a frame of academic excellence. The doctoral candidate's work should be presented in a dissertation or thesis prepared under the supervision of a tutor or director, and reviewed by a Doctoral Committee. This Committee should be composed of examiners external to the program, and at least one of them should also be external to the institution. The academic degree of Doctor is received after a successful defense of the candidates dissertation. Currently, there are approximately 2,151 postgraduate careers in the country, of which 14% were doctoral degrees. Doctoral programs in Argentina are overseen by the Comision Nacional de Evaluacion y Acreditacion Universitaria, which is a decentralized agency in Argentinas Ministry of Education, Science and Technology.

## Germany
A research doctorate usually takes three to five years to complete. In Germany, most doctorates are awarded with specific designations for the field of research instead of a general "PhD" for all fields. The degree is written in front of the first name for addresses (within texts, the abbreviation "Dr." is common) and accompanies the person's name (unlike in German-speaking Switzerland).
There are no first degree doctorates but medical students can obtain a "Dr. med." after one semester of mostly undergraduate research or data evaluation. The "Dr. med." is not equivalent to a PhD but to a Masters degree. Medical Students going into research can obtain a research doctorate in some subjects, such as molecular medicine or human biology.
Upon the completion of the Habilitationsschrift a senior doctorate (habil.) is awarded. This senior doctorate is known as the habilitation. It is not a degree, but an additional qualification. It authorizes the owner to teach at (German) universities ("facultas docendi"), plus qualifies the holder of the "habil." to teacher in a certain subject ("venia legendi"). This or an equivalent professional experience is - traditionally - the necessary prerequisite for a position of Privatdozent and Professor. Now, with the Bachelor/Master model and the Juniorprofessoren to be introduced, this has already changed partially.

## Spain
Doctor Degrees are regulated by Royal Decree (R.D. 778/1998), Decreto Real (in Spanish). They are granted by the University on behalf of the King, and its Diploma has the force of a public document. The Ministry of Science keeps a National Registry of Theses called TESEO . According to the National Institute of Statistics (INE), less than 5% of M.Sc. degree holders are admitted to Ph.D. programs, and less than 10% of 1st year Ph.D. students are finally granted a Doctorate.
All doctoral programs are of research nature. A minimum of 5 years of study are required, divided into 2 stages:
1) A 3-year long period of studies, which concludes with a public dissertation presented to a panel of 3 Professors. If the projects receives approval from the university, he/she will receive a "Diploma de Estudios Avanzados" (part qualified doctor).
2) A 2-year (or longer) period of research. Extensions may be requested for up to 10 years. The student must write his thesis presenting a new discovery or original contribution to Science. If approved by his "thesis director", the study will be presented to a panel of 5 distinguished scholars. Any Doctor attending the public presentations is allowed to challenge the candidate with questions on his research. If approved, he will receive the doctorate. Four marks can be granted (Unsatisfactory, Pass, "Cum laude", and "Summa cum laude"). Those Doctors granted their degree "Summa Cum Laude" are allowed to apply for an "Extraordinary Award".
A Doctor Degree is required in order to apply to a teaching position at the University.
The social standing of Doctors in Spain is evidenced by the fact that only Doctors and Grandees/Dukes can take seat and cover their heads before the King. All Doctorate Degree holders are reciprocally recognized as equivalent in Germany and Spain ("Bonn Agreement of November 14th 1994").

## United Kingdom
All doctorates (except for those awarded honoris causa) granted by British universities are research doctorates in the sense described above, in that their main (and in many cases only) component is the submission of a thesis or portfolio of original research, examined by an expert panel appointed by the university.
Even the relatively new 'vocational doctorates' such as the EngD, EdD, DSocSci and DClinPsych require the submission of a body of original research of a similar length to a PhD thesis. In the case of the EngD, however, this might be in the form of a portfolio of technical reports on different research projects undertaken by the candidate as opposed to a single, long monographical thesis. Another important difference is that traditional PhD programs are mostly academic-oriented and normally require full-time study at the university, whereas, in an EngD program, the candidate typically works full-time for an industrial sponsor on application-oriented topics of direct interest to the partner company and is jointly supervised by university faculty members and company employees.
The PhD itself is a comparatively recent introduction to the UK, dating from 1917. It was originally introduced in order to provide a similar level of graduate research training as was available in several other countries, notably Germany and the USA. Previously, the only doctorates available were the higher doctorates, awarded in recognition of an illustrious research career.
The universities of Oxford and Sussex denote the degree of Doctor of Philosophy with the postnominal initials DPhil. The University of York also did this for some years, switching to the more conventional PhD quite recently.

### Higher doctorates in the United Kingdom
Higher doctorates are awarded in recognition of a substantial body of original research undertaken over the course of many years. Typically the candidate will submit a collection of work which has been previously published in a peer-refereed context. Most universities restrict candidacy to graduates or academic staff of several years' standing. The most common doctorates of this type are those in Divinity (DD), Medicine (MD or DM), Laws (LLD), Civil Law (DCL), Music (DMus or MusD), Letters (DLitt or LittD) and Science (DSc or ScD).
Of these, the DD historically ranked highest, theology being the senior faculty in the mediaeval universities. The degree of Doctor of Canon Law was next in the order of precedence, but (except for a brief revival during the reign of Mary Tudor) did not survive the Protestant reformation, a consequence of the fact that the teaching of canon law at Cambridge and Oxford was forbidden by Henry VIII, founder of the Church of England. The DMus was, historically, in an anomalous situation, since a candidate was not required to be a member of Convocation (that is, to be a Master of Arts). The DLitt and DSc are relatively recent innovations, dating from the latter part of the 19th century.

### Honorary doctorates in the United Kingdom
Most British universities award degrees honoris causa in order to recognise individuals who have made a substantial contribution to a particular field.  Usually an appropriate higher doctorate is used in these circumstances, depending on the achievements of the candidate. However, some universities, in order to differentiate between honorary and substantive doctorates, have introduced the degree of Doctor of the University (DUniv) for these purposes, and reserve the higher doctorates for formal academic research.

## United States

### Research doctorate in the United States
The most common research doctorate is the Doctor of Philosophy (Ph.D.). This degree was first awarded in the U.S. at the 1861 Yale University commencement. The University of Pennsylvania followed shortly thereafter in 1870, while Harvard (1872) and Princeton (1879) also followed suit.
The requirements for obtaining Ph.D.s and other research doctorates in the U.S. typically entail successful completion of pertinent classes, passing of a comprehensive examination, and defense of a dissertation.

### Professional doctorates in the United States
In the United States, there are numerous degrees which incorporate the word "doctor" and are known as "professional doctorates." Such fields include audiology, chiropractic, dentistry, law, medicine, occupational therapy, optometry, osteopathic medicine, pharmacy, physical therapy, podiatry, practical theology, psychology, veterinary medicine, and many others that usually require such degress for licensure.  Generally, these degrees are considered "first professional degrees."
The primary difference between a professional doctorate (such as in the fields of medicine and law) and a research doctorate is that the former are, with few exceptions, not a terminal degree - that is, it is not the highest level of academic achievement in that field.  In addition, the professional degree usually does not focus primarily upon research, which is the central component of doctoral and most master's level research degrees. In addition, the research doctorate will require the creation of an original idea adding to the body of knowledge in the field, which is not a requirement of the professional doctorate.  Some law schools and a small number of medical schools require that the candidate perform original research and write a formal research paper; all accredited law schools have a writing requirement, but some allow it to be satisfied by a professional, as opposed to an academic-research, writing.  Even when not a requirement, most medical students still conduct some form of academic research before residency, often leading to publication. The typical minimum term for such a degree (M.D.) is 4 years past postsecondary education.  In addition, in many academic fields (such as law) the professional degree is the norm for academic and research careers.

### Professional doctorates in Korea and Japan
As part of a reform plan adopted in 2004, South Korea is creating a system of American-style graduate law schools which will award a Juris Doctor (professional doctoral) degree. Only graduates of these law schools, scheduled to matriculate their first students in 2009, will be eligible to take the bar exam. In Japan, a similar reform was started in 2004 and the degree of Juris Doctor is awarded to graduates of three year graduate studies in law.