Public service announcement:
Radio and television stations allow nonprofit organizations and schools to submit information about their organization, upcoming events, and other interesting facts by means of a PR tool called the public service announcement (PSA). The PSA is similar to media advisories or event calendar listings with one important difference: PSAs typically have a specific action-oriented message timed to be spoken by the radio jockey in either 30 or 60 seconds. The PSA encourages listeners and viewers to volunteer or come to a specific event.
Some television stations may use an organization's own videotape about the event or topic--provided the tape is high quality. Many television stations, however, request a small payment--about $200--to "guarantee" placement of your library's PSA. If you've ever stayed up late and watched television, you'll note that most topical messages such as those about quitting smoking or getting a hearing check are aired late at night to preserve regular viewing hours for paying advertisers.