In its strictest sense, Indie refers to music released by artists who are independent or signed to independent record labels (that is labels not affiliated with the 'big 4' majors: EMI, Universal, Sony, and Warner Bros). The inference is that the major labels sell music as a product because they are more motivated by money than art, and therefore 'indie' music is preferable because it retains its artistic integrity.

However, over the years the meaning of 'indie' has changed and its definition is now highly debatable.

Initially the kind of music which was often independent was rock aimed slightly left of the mainstream. This incorporated styles also known as 'college rock', such as the R.E.M. album Murmur; 'post-punk' such as British band The Fall; 'noise rock' such as Sonic Youth; and guitar-based pop such as The Smiths.

Now, indie seems to refer more to a demographic of people who listen to all these strands of rock, while also dipping into non-rock styles such as electronic dance music and hip-hop. For many people it has lost its reference to the company which funds an artist or record, which is now seen as only marginally relevant. This is because indie-rock now appeals to a size of audience big enough to justify major-label involvement, so many indie-rock bands such as Interpol, The White Stripes and Hot Chip have retained their credibility within the indie community despite their affiliation with big business. Artists like M.I.A. and LCD Soundsystem, who share closer musical signposts to hip-hop and disco than they do to rock music, have nevertheless been accepted into the indie fold, further blurring the definition. Others might argue that indie refers to a mindset that values a certain kind of musical aesthetic, though pinpointing exactly what that aesthetic is is problematic.