Effect: This is the result of a cause or some kind of event. This is a noun. Affect: This is the action of causing an effect. This is a verb. The sun created a negative effect on her skin. Her good deed affected his opinion of her.

Hi Sue, In general, effect is a noun, and affect is a verb (viz. Aura's definition). However, both can be used as verbs! "To effect" means "to put something into effect (action)". "This information will affect our experiment" = the information will influence the results of the experiment. "This information will effect our experiment" = the information will be used to get the experiment started. Even good native English speakers get tripped up by this one.

effect is usually reaction to an action. affect is usually negative reaction to an action.