Abstinence is the only absolute method of not getting pregnant. Abstinence from all forms of sex - vaginal, anal, and oral - is the only absolute method of eliminating your chances of acquiring a sexually transmitted disease.

But many people practice abstinence for reasons other than avoiding STDs and pregnancy. For some it is a way of life, for others, personal or religious beliefs require refraining from sexual activity.

In many cultures throughout the world, including much of Western Civilization, sexual activity before marriage or outside of marriage is discouraged or legally prohibited. This was an attitude shared by Americans through most of the history of the United States until the 'sexual revolution' of the 1960's and 1970's.

Since then, premarital sex has generally been acknowledged as common occuring, if not commonly accepted. This shift in cultural attitudes has been accompanied by a change in sexual education. In the late twentieth century, educators began to suggest abstinence-only sexual education programs were not only ineffective, but contributed to the spread of teen pregnancy and sexually transmitted diseases. Abstinence-only sexual education programs were not discouraging teenagers from sexual activity and didn't allow for a realistic discussion of available options for both birth control and to prevent STDs.

The twentieth century saw an increase in political support for abstinence-only education in the United States due to new federal funding initiatives. It is estimated that more than one-third of U.S. states are teaching some form of federally funded abstinence-only education programs. Here's more information on abstinence-only education in the United States.