Pop music is a genre of popular music that originated in its modern form in the United States and United Kingdom during the mid-1950s. The terms "popular music" and "pop music" are often used interchangeably, although the former describes all music that is popular and includes many styles. "Pop" and "rock" were roughly synonymous terms until the late 1960s, when they became increasingly differentiated from each other. 

Although pop music is seen as just the singles charts, it is not the sum of all chart music. Pop music is eclectic, and often borrows elements from other styles such as urban, dance, rock, Latin, and country; nonetheless, there are core elements that define pop music. Identifying factors include generally short to medium-length songs written in a basic format (often the verse-chorus structure), as well as common use of repeated choruses, melodic tunes, and hooks. 

David Hatch and Stephen Millward define pop music as "a body of music which is distinguishable from popular, jazz, and folk musics". According to Pete Seeger, pop music is "professional music which draws upon both folk music and fine arts music". Although pop music is seen as just the singles charts, it is not the sum of all chart music. The music charts contain songs from a variety of sources, including classical, jazz, rock, and novelty songs. Pop music, as a genre, is seen as existing and developing separately. Thus "pop music" may be used to describe a distinct genre, designed to appeal to all, often characterized as "instant singles-based music aimed at teenagers" in contrast to rock music as "album-based music for adults".
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According to Pete Seeger