What is the difference between "affect" and "effect"? I always use the wrong one.

Simple rule: Affect is usually a VERB (an action). Effect is usually a NOUN (a result). Examples: "The rain AFFECTED our plans" (verb — rain did something). "The rain had a bad EFFECT on our plans" (noun — result). Memory trick: RAVEN — Remember: Affect = Verb, Effect = Noun. Exception (less common): Effect can be a verb meaning "to bring about": "The new policy effected major changes." Affect can be a noun in psychology: "The patient showed flat affect." For school level, always use affect as verb and effect as noun.