Idol (アイドル, aidoru) anime and manga are a category of Japanese fictional media centered on idols, a type of entertainer in their teens and early 20s marketed to have a close relationship with their fans and commercialized through merchandise. Beginning in the 1980s, anime was used as a vehicle to promote an up-and-coming idol's singing career, but has since then created various anime media mix projects centering on fictional singers.
From: Wikipedia