There are a number of cultural and philosophical traits which could be more useful in pinpointing what "indie" is about than specific musical styles or commercial ownership. Indie artists are concerned more with self-expression than commercial considerations (though, again, this is a stance that is affected by many artists, including hugely commercially successful ones). A do-it-yourself sensibility, which originated with punk in the 1970s, is often associated with indie, with people in the scene being involved in bands, labels, nights and zines. Indie often has an internationalist outlook, which stems from a sense of solidarity with other fans, bands and labels in other countries who share one's particular sensibilities; small indie labels will often distribute records for similar labels from abroad, and indie bands will often go on self-funded tours of other cities and countries, where those in the local indie scenes will invariably help organize gigs and often provide accommodation and other support. In addition, there is also a strong sense of camaraderie that emerges from a selflessness among indie bands and often results in collaborations and joint tours.

Indie artists of any particular time often go against the prevailing trends (for example, the twee pop movement that started in the 1980s was a reaction against the testosterone-fueled swagger of rock). A 'lo-fi' aesthetic (i.e., an often deliberate lack of polish and a more "authentic" roughness and imperfection) has often been associated with indie, particularly when slick, polished recordings were the preserve of the commercial music industry; this line has since become blurred, in a world where high-quality recordings can be made increasingly easily with inexpensive computer-based recording systems and where commercial production teams often deliberately utilize a "lo-fi" sound.

There are several subcategories which music from the overall indie scene are often grouped broadly into. Music ranging from alternative rock to punk rock to experimental music has long existed in indie scenes, often independent from one another. Indie rock and indie pop are the most common groupings that conform to an "indie" sound. The difference between these is difficult to pick up from the instrumentation or sound, as both genres include distorted guitar-based music based on pop-song conventions. If anything, the key distinction comes not from instrumentation or structure but from how strictly they follow cultural constructions of rockist "authenticity". There is also indie dance, which comes from a fusion of indie pop and electronic/dance music. Crossover between electronica (mostly glitch) resulted in so-called indietronic, electronic indie or indie electronic, for example some artists on the German Morr Music label, The Firebird Band, The Postal Service, or Fever Marlene.