J-pop is an abbreviation of Japanese pop. It refers to Western-influenced Japanese popular music. The term J-pop was coined by J-Wave, an FM radio station, to denote what was once called "New Music." The term is widely used in Japan to describe many different musical genres including pop, rock, dance, rap, and soul. In the Nagoya area the term Z-pop is used to describe songs popular in the region. J-rock, Visual Kei and J-rap are generally considered to fall under the J-pop umbrella as well. Singers of J-pop include both popular musicians and seiyū.
http://www.japaneselifestyle.com.au/culture/j-pop_history.html
