What is a Public Service Announcement? If you don't know what it is, Google it. In your own words, now tell me what it is? What are they used for? Can you recall an example of a PSA you've seen before?

A public service announcement is an announcement of information that interests a group of people. They are used to spread a message/important information many people at once, usually over radio or television.  An example of a public service announcement would be information over the radio/television about dangerous weather, like a tornado or hurricane.