A term, "chops" used by jazz cats refer to someone who can really play his instrument in a virtuosic way. Like in 'he has some chops', meaning 'he smokes' or 'he can play well'
A shredder is the rock version of the guys with chops.

Shredding is a kind of music, mostly intrumental guitar, where the guys play out of this world solos.
Let's say that if you like to fast forward to a solo in a song, you are a good client for shred, for shredders think songs are the boring part between solos :p

ps: for anyone who might think I hate shred/shredding/shredders, have a listen there: http://www.lalimace.com and also, what is wrong with my description, I think it's rather accurate :)