AC - Adult Contemporary stations play a mix of current and past hits tailored to adult listeners. The format is known for its broad appeal. Although tastes can vary depending on the region and the specific demographic. Adult contemporary music (AC) is a form of radio-played popular music, ranging from 1960s vocal and 1970s soft rock music to predominantly ballad-heavy music of the 1980s to the present day, with varying degrees of pop, soul, R&B, quiet storm and soft rock influence. 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 most commonly used as background music. AC radio often targets the 25–44 age group, the demographic that has received the most attention from advertisers since the 1960s. A common practice in recent years of adult contemporary stations is to play less newer music and more hits of the past, even some songs that never even charted the AC charts. AC has spawned subgenres including "hot AC", "soft AC" (also known as "lite AC"), "urban AC", and "Christian AC" (a softer type of contemporary Christian music) and Smooth Jazz. Some stations play only "hot AC", "soft AC", or only one of the variety of subgenres. Over the 2000s, the AC market gained an increased presence in the music industry, as its radio formats were popular nationwide—Smooth jazz and "Urban AC" stations were ubiquitous in the East Coast, while Soft rock and "adult standards" stations were common in the Midwest, and pop-oriented "Hot AC" and "world music"/Hispanic AC stations were easily found in the West Coast and the "Sun Belt". This led to the presence of numerous genres on the AC charts, often crossing to the "pop" charts, winning over many critics in the need to define AC, and increased the tolerance and acceptance of AC music into mainstream day-to-day radio play.