When should I use "effect" vs. "affect"?

Effect and affect are two of the most commonly confused words in English. Although they sound similar, the two words are different parts of speech. Effect is the noun. Affect is the verb. You can remember this easily by remembering that affect is an action, and those both start with the letter a.

Effect usually means the end result. For example, you might say, he had an effect on me. Studies often talk about effects of different processes. You might read an article about the effect of income level on educational success or the effect of high-fat diets in diabetic patients. Remember, effect is the end result; these both start with e.

Affect usually means the action that results in an effect. You could say the weather affected your arthritis. Someone might say that a trip to the symphony affected them spiritually. You might remind your child not to let a bully's words affect them. Remember, affect is an action; these both begin with a.

Exceptions

As always, there are exceptions to the noun/verb rule. In some cases, effect can be a verb, but we use it rarely. It is always used with an object, and it means to bring about. Your boss might tell you to effect these changes to company policy next week.

Affect can also be a noun, but it is limited to psychology and medical uses. It means a feeling or emotion, specifically the way a person shows their emotion. A psychiatrist or nurse may record that a patient has a flat affect, which means they appear to have no emotions. A pleasant affect means a person is presenting as happy.