In legal definitions for interpersonal status, a single person is someone who is not in a relationship or is "unmarried". If a marriage is annulled, however, or it is found to have been void ab initio (i.e. not valid in law to start with), and assuming the person was not married previously, that individual is single, rather than unmarried. In that situation, the law behaves as though the parties thought they were married when, in actuality, they were not. The term single in its common usage is often referred to someone who isn't involved in any type of romantic relationship, whether it would be dating, engagement, or marriage. Both single and unmarried people may participate in dating rituals and other activities to find a long-term partner or spouse. However, in some cases single people are not interested in marriage, domestic partnership, or other types of formal, committed relationships.
People may remain single for a variety of reasons, including: financial and emotional or physical health issues, stress in the family, time constraints, education, career, personal preferences, advanced age, social fears or love-shyness, and even living in a society or locality where there aren't enough people of the sex one is attracted to. Certain careers and positions require that people remain single. Sometimes, this is coupled with celibacy or chastity, either for secular or for religious reasons, such as priests, nuns and monks in certain faiths. Loneliness can occur for some people who look for but cannot find anyone they might wish to date, especially for those suffering the loss of companionship following divorce or bereavement. Some single people, however, regard and appreciate solitude as an opportunity.
Certain situations assume that a person is married; this includes laws that vary depending on the country. For example, in the United States, Social Security relies on spouses, children, and other family, until the point that a given individual is legally elderly (65 years of age or over), or if the person has a significant disability (of any age; see Social Security Disability). It is generally assumed an individual's family member(s) will inherit or replace the holder when they are deceased. Therefore, except for the elderly and the legally disabled, US Social Security is not a benefit single people can claim.
United States 
According to the United States Bureau of the Census, the fastest-growing household type since the 1980s has been the single person. Previously both socially uncommon and unaccepted due to perceived roles, public awareness, modern socioeconomic factors and increasingly available popular and lengthier education and careers have made the single lifestyle a viable option for many Americans, especially after the Vietnam War.
United Kingdom 
Similar to the United States, single-person households are increasingly popular in the United Kingdom. In recent years, studies have found that more citizens value career over personal relationships. The single-person households have also been spreading due to the high self-esteem it offers.
In Japan, it is not uncommon for citizens to choose to remain single. This has been illustrated with many public figures and celebrities. Women typically value friendships over romantic relationships and many continue to have jobs and marry later or forego marriage completely.
Single men are often called bachelors. Single women are sometimes called bachelorettes, especially in festive contexts in American English; but the historic term is spinster. Contrary to popular belief, a spinster is any woman above the age of majority who has never been married. She is not necessarily an elderly woman. Catherinette was a traditional French label for girls of 25 years old who were still unmarried by the Feast of Saint Catherine. The term sheng nu is used to describe unmarried women who are in mid to late twenties in China and East Asia.
Targeted commerce 
In the United States, young singles have substantial purchasing power. They have relatively few financial burdens, tend to be early purchasers of fashion, are recreation oriented, and purchase travel and kitchen goods frequently. Members of this group frequently have large disposable incomes with which they indulge themselves. They are heavily targeted by product and service marketers.
Dating services are an especially targeted and advertised service for singles. The growth of the dating services and dating events industry has been so drastic that the phrase "dating–industrial complex" (reminiscent of President Dwight D. Eisenhower's term "military industrial complex") has been coined to capture the amount of money and manpower devoted to dating services for singles.
Singles events have been an area of particular growth in singles-related commerce. Many events are aimed at singles of particular affiliations, interest, or religions.Some of the most strongly attented such events are the Christmas Eve party targeted at young Jewish singles in major cities in North America, particularly the Matzo Ball and its big city competitors.A variety of other religious organizations' singles events are also very popular. However, dating via religious-sponsored singles events has also been criticized for fostering invasion of daters' privacy and undue expectations.
See also 
- China's Gender Gap Leaves Millions of Single Men: The nation's one-child policy could leave 24 million bachelors by the year 2020
- AFP/Discovery News, January 12, 2010Alex Williams, "The New Math on Campus", New York Times, February 5, 2010
- Scott, Jacqueline L.; Treas, Judith; Richards, Martin (2004). The Blackwell companion to the sociology of families. Wiley-Blackwell. pp. 377–378. ISBN 0-631-22158-1.
- "Single living is the new way to find happiness". Times Online. August 3, 2005. Retrieved June 2, 2010.
- Schefft, J (2007). Better Single Than Sorry. Harper Collins. p. 12.
- David Needham, Rob Dransfield, et al. (1999) Business for Higher Awards, p. 33
- Leon G Schiffman and Leslie Lazar Kanuk. (2004) Consumer Behavior, p. 358
- Jarice Hanson. (2007) 24/7: how cell phones and the Internet change the way we live, work, and play, p. 81
- Jane Ganahl. "The downside of cyber-romance", San Francisco Chronicle, March 28, 2004
- Roy S. Gutterman. "There's a Science (and Terminology) to the Process of Getting Rejected", The (Philadelphia) Jewish Exponent, April 3, 2008
- Larry Glanz and Robert H. Phillips. (2003) Guy Gets Girl, Girl Gets Guy: Where to Find Romance and What to Say When You Find It, p. 59
- Monica B. Morris. (2005) Falling in love again: the mature woman's guide to finding romantic fulfillment, p. 80
- Jessica Gresko, Dec. 24 Becomes Party Night for Jewish Singles, Associated Press (Washington Post), December 24, 2006
- William July, II. (2003) Confessions of an ex-bachelor, p. 113