Assassin is an agile champion that specializes in killing or disabling roaming targets picking them of as they try to replenish HP.
Fighter are close range combatants that possess a mix of offensive and defensive capabilities.
Mage is a magic damage dealer and an important role in any team composition.
Marksman are typically played in either the top or bottom lanes with some sort of support.
Support role is to aid and help protect your allies in any situation.
Tank are durable, front-line champions that help lock down enemies and start fights.