According to our friend Wikipedia, "Adult contemporary music, frequently abbreviated AC, is a type of radio format that plays mainstream contemporary popular music, excluding hip hop, hard rock, some teen pop music, and rhythmic dance tracks, which is intended for a mature adult audience, especially for people who are 16 and older."
Mostly, the one I listen to doesn't play much modern stuff, it usually has stuff from the 80s and 90s, stuff like light rock, etc. Like WLIX, I don't switch to it often.