well, that's what wiki says.
"In popular music, independent music, often generally abbreviated as "indie", is a term used to describe independence from major commercial record labels and an autonomous, Do-It-Yourself approach to recording and publishing."
if you're refering to the genre, it would be indie rock. (also taken off wiki)
"Indie rock is a genre of rock music that originated in the United States and the United Kingdom in the 1980s. The term is often used to describe the means of production and distribution of independent underground music, as well as the style of music that was first associated with this means of production.[1] Indie rock artists are known for placing a premium on maintaining complete control of their music and careers, releasing albums on independent record labels (sometimes self-owned and operated) and relying on touring, word-of-mouth, airplay on independent or college radio stations, and in recent years, the Internet for promotion. Musicians classified as indie rock are typically signed to independent record labels, rather than major record labels, although there are many examples of indie musicians switching to major labels mid-career. This practice blurs the lines between indie and mainstream music and is often the subject of debate amongst fans. Indeed, some bands that have spent most of their careers on major labels are still occasionally referred to by the press as indie rock because of their sound or aesthetic."
then again, this info comes from wiki...