Adult contemporary music (AC) is a style of music, ranging from 1960s vocal and 1970s soft rock music to predominantly ballad-heavy music of the present day, with varying degrees of easy listening, soul, rhythm and blues, and rock influence. Adult contemporary is rather a continuation of the easy listening and soft rock style that became popular in the 1960s and 1970s with some adjustments that reflect the evolution of pop/rock music.
Adult contemporary tends to have lush, soothing and highly polished qualities where emphasis on melody and harmonies is accentuated. It is usually melodic enough to get a listener's attention, and is inoffensive and pleasurable enough to work well as background music. Like most of pop music, its songs tend to be written in a basic format (often the verse-chorus structure), as well as the common employment of repeated choruses.
Adult contemporary is heavy on romantic ballads which mostly use acoustic instruments (though bass guitar is usually used) such as acoustic guitars, pianos, saxophones, and sometimes an orchestral set. The electric guitars are normally faint and high-pitched. However, recent adult contemporary music may usually feature synthesizers (and other electronics, such as drum machines).
AC radio may play mainstream music, but they will exclude "hip hop", "heavy metal", youth-oriented "hard rock", "teen pop" music, and rhythmic "dance tracks", as they are less popular amongst the target demographic of these radio stations, which is intended for an adult audience. Radio stations playing this format will often target the 18–54 age group, also the demographic that has received the most attention from advertisers since the 1960s.
Over the years, AC has spawned numerous sub-genres: "hot AC", "soft AC" (also known as "lite AC"), "urban AC", "rhythmic AC", and "Christian AC" (i.e., a softer type of Contemporary Christian music). Some radio stations play only "hot AC", "soft AC", or only one of the variety of sub-genres. Therefore, it is not usually considered a specific genre of music; it is merely an assemblage of selected tracks from musicians of many different genres.