User blog comment:Themguyman/Picking your next champion/@comment-75.140.108.3-20130116210041/@comment-3557616-20130117062806

Some different roles:

AD carry, main damage dealer.

AP carry, spell-based damage dealer, less damage but more CC than AD carry.

Tank, damage sponge.

Support, champion who places wards, gets aura items, heals teammates, and backs up the carry early game.

Jungler, champion who roams around the jungle to farm, and occasionally comes out to attack those in the lanes.

Assasin, mobile champion capable of dealing lots of damage very quickly, good at taking out carries.