Pop music is the genre of popular music that produces the most hits. A hit is a song that sells many copies, and the latest hits are listed every week on the charts. To get on the charts, a song must be released as a single, although most singles are also released on an album. Songs that become hits almost always share certain features that are sometimes called the pop-music formula. They have a good rhythm, a catchy melody, and are easy to remember and sing along to. They usually have a chorus that’s repeated several times and two or more verses. Most pop songs are between two and five minutes long, and the lyrics are usually about the joys and problems of love and relationships. Pop songs are produced by groups like the boy band One Direction and the girl group Girls’ Generation, and by pop singers like Justin Bieber and Madonna