Demographics
Demographics refers to selected population characteristics as used in government, marketing or opinion research, or the demographic profiles used in such research. (Note the distinction from demography, see below.) Commonly-used demographics include race, age, income, disabilities, mobility (in terms of travel time to work or number of vehicles available), educational attainment, home ownership, employment status, and even location. Distributions of values within a demographic variable, and across households, are both of interest, as well as trends over time. Demographics are frequently used in economic and marketing research.
Demographic trends describe the changes in demographics in a population over time.  For example, the average age of a population may increase.  It may decrease as well as certain restrictions may be in place, for instance like in China if the population is high.

# Demographics vs Demography
The term demographics as a noun is often used erroneously in place of demography, the study of human population, its structure and change. Although there is no absolute delineation, demography focuses on population structure, processes and dynamics, whereas demographics is most often used in the fields of media studies, advertising, marketing, and polling, and should not be used interchangeably with the term "demography" or (more broadly) "population studies".  'Demographic' as an adjective can refer to either, e.g., demographic transition

# Demographic variables
Demographic Marketers and other social scientists often group populations into categories based on demographic variables. Some frequently used demographic variables are:
- Age
- Sex / Gender
- Race/ Ethnicity
- Location of residence
- Socioeconomic status (SES)
- Religion
- Marital status
- Ownership (home, car, pet, etc.)
- Language
- Mobility
- Life cycles (fertility, mortality, migration)

# Demographic profiles in marketing
Marketers typically combine several variables to define a demographic profile. A demographic profile (often shortened to "a demographic") provides enough information about the typical member of this group to create a mental picture of this hypothetical aggregate. For example, a marketer might speak of the single, female, middle-class, age 18 to 24 demographic.
Marketing researchers typically have two objectives in this regard: first to determine what segments or subgroups exist in the overall population; and secondly to create a clear and complete picture of the characteristics of a typical member of each of these segments. Once these profiles are constructed, they can be used to develop a marketing strategy and marketing plan.

# Generational cohorts
A generational cohort has been defined as "the aggregation of individuals (within some population definition) who experience the same event within the same time interval". The notion of a group of people bound together by the sharing of the experience of common historical events due to their birth in a particular period of time was first introduced by Karl Mannheim in the early 1920s. Today the concept has found its way into popular culture through well known epitomes like "baby boomer" and "gen-Xer".

# Cohorts in the United States
A study by William Strauss and Neil Howe, in their books Generations and Fourth Turning, looked at generational similarities and differences going back to the 15th century and concluded that over 80 year spans, generations proceed through 4 stages of about 20 years each. The first phase consists of times of relative crisis and the people born during this period were called "artists". The next phase was a "high" period and those born in this period were called "prophets". The next phase was an "awakening period" and people born in this period were called "nomads". The final stage was the "unraveling period" and people born in this period were called "heroes". The most recent "high period" occurred in the 50s and 60s (hence baby boomers are the most recent crop of "prophets").
The most definitive recent study of US generational cohorts was done by Schuman and Scott (1989) in 1985 in which a broad sample of adults of all ages were asked, "What world events over the past 50 years were especially important to them?". They found that 33 events were mentioned with great frequency. When the ages of the respondents were correlated with the expressed importance rankings, seven distinct cohorts became evident. Today the following descriptors are frequently used for these cohorts:
- Depression cohort (born from 1912 to 1921)
Memorable events: The Great Depression, high levels of unemployment, poverty, lack of creature comforts, financial uncertainty
Key characteristics: strive for financial security, risk averse, waste-not-want-not attitude, strive for comfort
- Memorable events: The Great Depression, high levels of unemployment, poverty, lack of creature comforts, financial uncertainty
- Key characteristics: strive for financial security, risk averse, waste-not-want-not attitude, strive for comfort
- Pre 'World War II cohort' (born from 1922 to 1927)
Memorable events: men leaving to go to war and many not returning, the personal experience of the war, women working in factories, focus on defeating a common enemy
Key characteristics: the nobility of sacrifice for the common good, patriotism, team player
- Memorable events: men leaving to go to war and many not returning, the personal experience of the war, women working in factories, focus on defeating a common enemy
- Key characteristics: the nobility of sacrifice for the common good, patriotism, team player
- World War II cohort (born from 1928 to 1945)
Memorable events: sustained economic growth, social tranquility, The Cold War, McCarthyism
Key characteristics: conformity, conservatism, traditional family values
- Memorable events: sustained economic growth, social tranquility, The Cold War, McCarthyism
- Key characteristics: conformity, conservatism, traditional family values
- Baby Boomer cohort #1 (born from 1946 to 1954)
Memorable events: assassinations of JFK, Robert Kennedy, and Martin Luther King, political unrest, walk on the moon, Vietnam War, anti-war protests, social experimentation, sexual freedom, civil rights movement, environmental movement, women's movement, protests and riots, experimentation with various intoxicating recreational substances
Key characteristics: experimental, individualism, free spirited, social cause oriented
- Memorable events: assassinations of JFK, Robert Kennedy, and Martin Luther King, political unrest, walk on the moon, Vietnam War, anti-war protests, social experimentation, sexual freedom, civil rights movement, environmental movement, women's movement, protests and riots, experimentation with various intoxicating recreational substances
- Key characteristics: experimental, individualism, free spirited, social cause oriented
- Baby Boomer cohort #2 (born from 1955 to 1964)
Memorable events: Watergate, Nixon resigns, the cold war, the oil embargo, raging inflation, gasoline shortages
Key characteristics: less optimistic, distrust of government, general cynicism
- Memorable events: Watergate, Nixon resigns, the cold war, the oil embargo, raging inflation, gasoline shortages
- Key characteristics: less optimistic, distrust of government, general cynicism
- Generation X cohort (born from 1965 to 1979)
Memorable events: Challenger explosion, Iran-Contra, social malaise, Reaganomics, AIDS, safe sex, fall of Berlin Wall, single parent families
Key characteristics: quest for emotional security, independent, informality, entrepreneurial
- Memorable events: Challenger explosion, Iran-Contra, social malaise, Reaganomics, AIDS, safe sex, fall of Berlin Wall, single parent families
- Key characteristics: quest for emotional security, independent, informality, entrepreneurial
- Generation Y cohort also called N Generation (born from 1980 to 2001)
Memorable events: rise of the internet, September 11 attacks, cultural diversity, 2 wars in Iraq
Key characteristics: quest for physical security and safety, patriotism, heightened fears, acceptance of change, technically savvy, environmental issues
- Memorable events: rise of the internet, September 11 attacks, cultural diversity, 2 wars in Iraq
- Key characteristics: quest for physical security and safety, patriotism, heightened fears, acceptance of change, technically savvy, environmental issues

### US Demographic birth cohorts
The US Census Bureau considers the following demographic birth cohorts based on birth rate, which is statistically measurable:
- Classics (born from 1900 to 1920)
(the last American cohort in which the population pyramid takes on the standard "step" form for males and females)
- (the last American cohort in which the population pyramid takes on the standard "step" form for males and females)
- Baby Bust (I) (born from 1921 to 1945)
early cohort (born from 1921 to 1933)
late cohort (born from 1934 to 1945)
- early cohort (born from 1921 to 1933)
- late cohort (born from 1934 to 1945)
- Baby Boomers (born from 1946 to 1964)
Leading Edge Boomers (born from 1946 to 1957)
Trailing Edge Boomers (born from 1958 to 1964)
- Leading Edge Boomers (born from 1946 to 1957)
- Trailing Edge Boomers (born from 1958 to 1964)
- Baby Bust (II) (born from 1965 to 1976)
- Echo Boomers (born from 1977 to 1994)
Leading Edge (born from 1977 to 1990)
- Leading Edge (born from 1977 to 1990)
Subdivided groups are present when peak boom years or inverted peak bust years are present, and may be represented by a normal or inverted bell-shaped curve (rather than a straight curve). The boom subdivided cohorts may be considered as "pre-peak" (including peak year) and "post-peak". The year 1957 was the baby boom peak with 4.3 million births and 122.7 fertility rate. Although post-peak births (such as trailing edge boomers) are in decline, and sometimes referred to as a "bust", there are still a relative large number of births. The dearth-in-birth bust cohorts include those up to the valley birth year, and those including and beyond, leading up to the subsequent normal birth rate.

# Criticisms and qualifications of demographic profiling
Demographic profiling is essentially an exercise in making generalizations about groups of people. As with all such generalizations many individuals within these groups will not conform to the profile - demographic information is aggregate and probabilistic information about groups, not about specific individuals. Critics of demographic profiling argue that such broad-brush generalizations can only offer such limited insight that their practical usefulness is debatable.
Most demographic information is also culturally based. The generational cohort information above, for example, applies primarily to North America (and to a lesser extent to Western Europe) and it may be unfruitful to generalise conclusions more widely.