The Adult Top 40 (also known as Adult Pop Songs) chart is published weekly by Billboard magazine and ranks "the most popular adult top 40 as based on radio airplay detections measured by Nielsen Broadcast Data Systems." It is a format in which the genre is geared more towards an adult audience who are not into hard rock, hip hop, or adult contemporary fare. The main genres within this format are alternative rock and mainstream pop that is more adult-oriented. It is not to be confused with adult contemporary where rather lesser-known and more ballad-driven songs are played.