1. Originally a coined slang term from the 1980s for a graffiti artist that always kept a backpack on containing his finite music collection and more importantly his rattle cans, markers, and spray tips.
Although, mainly his music collection is what defines him/her as a backpacker. Most likely the music collection will consist of usually local underground rap/hip-hop music artists only. The sub-genre or sub-categoration of the music means nothing, as long as they are a local unsigned (no recording contract) artist.
A backpackers music selections are based upon three principals: 1) no mainstream, 2) you could never buy the music in a store, and 3) the music was given/sold to them "hand-to-hand" from the originating recording artist.
2. Modernly used derogatory term to describe someone who listens ONLY to Independent rap/hip-hop music, specifically (but not limited to) the nerd-rap sub-genre of the rap/hip-hop music. Most often used in reference to (but not limited by) white sub-urbanite rap/hip-hop music listeners that tend to dislike mainstream rap/hip-hop music, specifically (but not limited to) Gangsta rap.
Notes: Many Hip-Hop listeners from the 80s to early 90s agree that since the invention of the Internet, Underground has died along with Backpackers and there three main principals, hence this modernized definition incorporating Independent rap/hip-hop music and locality of artists lost. Hip-Hop listeners with twenty or more years of experience will often disagree on the definition of Backpacker with the new era of listeners who never have experienced hip-hop without the Internet.
Ex. for definition 1:
John 1ner, the local graff kid only listens to music that he buys at shows from local artists, he never buys music from the record store, unless it's in the local section and they are unsigned hype artists.
Ex. for definition 2:
Yo your boy Johny bugs me out with that nerd-rap stuff about comic books and emo relationships, fools such a backpacker, always dissin on Dre and Biggie.