The definition of pop music is constantly changing, but at any point in time it may be easiest to identify pop music as that which is successful on the pop music charts. For the past 50 years the most successful musical styles on the pop charts have continually changed and evolved.
People often confuse pop music with popular music. The New Grove Dictionary Of Music and Musicians, identifies popular music as the music since industrialization in the 1800′s that is most in line with the tastes and interests of the urban middle class. Pop music, on the other hand, has primarily come into usage to describe music that evolved out of the rock ‘n roll revolution of the mid-1950′s and continues in a definable path to today.
Since the mid-1950′s pop music has usually been identified as the music and the musical styles that are accessible to the widest audience. This means the music that sells the most copies, draws the largest concert audiences, and is played most often on the radio.