Genre of music, nicknamed after the independent labels which support lesser-known bands. Typically, the independent labels allow more "musical freedom", which results in a truer, less cookie-cutter sound that mainstream listeners do not immediately identify with. Indie rock draws inspiration from bands such as the Beatles, The Velvet Underground, and Radiohead.
Many indie rock bands are characterized by the use of unique or less-popular instruments. Subjectively (since music is subjective), indie rock cds typically sound less "perfect" than mainstream music, which typically grabs the attention of indie rock enthusiasts.
Indie rock is a mixture of many other genres, including alternative rock, folk music, electronica, even pop. It also tends to be very positive music, despite popular opinion.
More well-known rockers that are excellent introductions: The Killers, Death Cab for Cutie, Modest Mouse, Arctic Monkeys, Spoon, Yeah Yeah Yeahs
Others that are popular among indie rockers: The Flaming Lips, The Shins, Bright Eyes, The Decemberists, Wilco, The Magic Numbers, Mates of State, The Essex Green, Calexico, dios (malos), Clap Your Hands Say Yeah, Rilo Kiley, far too many to list. Find a Paste magazine and dig in.