What makes a band indie?

so its not really a style of music but an attitude towards corporate mainstream music correct?

Indie = Independent/Independently.
Therefore, a typical Indie band should be self-recorded and/or self-published or be signed to an independent record company. For example; a band signed with Sony would not be indie.


EDIT:
Yes, it's not so much a style; since there are Indie Screamo, metal, acoustic, pop bands etc. It's just an attitute and way of publishing music.

If they're on an independent label

Funny, I was GONNA ask the very same question here, but chose 2 other forums instead.

I've read some LONG debates about this on an indie forum & man, there really is No consensus.

Some say it's simply being on an indie label, while others insist it's a specific style.

Check this out:

http://youtube.com/watch?v=5rLLqdnGwqQ

theyre indie as long as theyre not signed to a big label

I don't know completely. Labels and such...But one thing I can think of, is that an indie band doesn't struggle to get fame, and cares solely on the music and meaning. They don't care if they're popular or mainstream. That's what makes a true band in my opinion.

Indie, is (was) supposed to be short for "Independent", as in a small record deal , and without major label distribution. But these days of every style having 150 sub-genres, i'm sure a lot of inexperienced ones are going round saying they love "Indie" music as a style in itself , LOL!