J-Pop
J-Pop: Japanese pop music. One of the DJs at J-WAVE, 81.3FM in Tokyo, originally coined the term, and it quickly became popular among music fans. If it's from Japan, and it's not classical or folk music, it's J-Pop.
J-Rock: A term used by foreign fans (but not in Japan) to refer to rock-style J-Pop
See also: Visual Kei
J-Rock: A term used by foreign fans (but not in Japan) to refer to rock-style J-Pop
See also: Visual Kei