wikipedia link to Public Service Announcements

A public service announcement (PSA) or community service announcement (CSA) is an advertisement broadcast on radio or television, for the public interest. PSAs are intended to modify public attitudes by raising awareness about specific issues. The most common topics of PSAs are health and safety. A typical PSA is part of a public awareness campaign to inform or educate the public about an issue such as smoking or compulsive gambling. Contrary to popular belief, political campaign advertisements are not PSAs.

Public service advertising campaigns are widespread around the world. Such advertising is generally produced and distributed on a cooperative basis by governmental agencies or nonprofit organizations acting in concert with private advertising and mass media companies. In most cases, the nonprofit provides the programming that is to be advertised, while the participating advertising agency and media companies provide creative services, media planning, and dissemination services on a pro bono basis.

From time to time a charitable organization releases a PSA enlists the support of a celebrity; examples include Michael J. Fox's PSAs in the U.S. supporting research into Parkinson's Disease and Crips street gang leader Stanley "Tookie" Williams speaking from prison to urge youth not to join gangs.

Some religious organizations produce PSAs on non-religious themes such as family values. Examples include the long-running homefront campaign[1] from The Church of Jesus Christ of Latter-day Saints, and campaigns by the Seventh-day Adventist Church and the United Methodist Church.

The military produces PSAs to recruit enlistees, in addition to paid advertising and sponsorship efforts.

In the U.S, the role of PSAs was affected by deregulation of the broadcasting industry in the 1980s. Previously, a broadcast license was assigned to a television or radio station that was expected to serve as a "public trustee" by airing PSAs (in addition to meeting other requirements).[2]

United States producers distribute traditional PSAs distributed to station directors.

Some television shows featuring very special episodes made PSAs after the episodes. For example, Conrad Bain of Diff'rent Strokes spoke two PSAs after the episodes dealing with child sexual abuse and hitchhiking.