Direct comparison
Affect vs effect
Affect is usually a verb meaning to influence something; effect is usually a noun meaning the result of that influence.
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Side-by-side comparison
| Dimension | Affect | Effect |
|---|---|---|
| Usual part of speech | A verb — an action word. | A noun — a thing or result. |
| Core meaning | To influence, change or have an impact on something. | The result, outcome or consequence produced by a cause. |
| Quick test | Can you replace it with "influence"? Then use affect. | Can you put "the" or "an" in front? Then use effect. |
| Typical example | The weather affected our plans. | The weather had an effect on our plans. |
| Position in a sentence | Usually takes a direct object (affect X). | Often follows an article or adjective (an effect, the effect, a side effect). |
| The exception | As a noun in psychology, affect means observable emotion or mood. | As a verb, effect means to bring about or accomplish (to effect change). |
| Pronunciation clue | As a verb, often a slightly reduced first syllable (uh-FECT). | Usually a clear short "e" at the start (ih-FECT). |
| Memory aid | A = Action, so Affect is usually the verb. | E = End result, so Effect is usually the noun. |
| Common error | Writing "the affect was huge" when you mean the result. | Writing "it effected me deeply" when you mean it influenced you. |
The 90 per cent rule and the exceptions
For most everyday sentences the rule is simple: affect is the verb and effect is the noun. Something affects you (verb), and it has an effect on you (noun). Memorise that pairing and you will be right the overwhelming majority of the time. The two exceptions trip people up because they reverse the parts of speech. To effect something (verb) means to bring it about or accomplish it — "the new manager effected sweeping changes". And in psychology and psychiatry, affect (noun, stressed on the first syllable) means a person’s observable emotional expression — "the patient presented with a flat affect". Outside those two specialist cases, stick with affect-verb and effect-noun.
Common questions
FAQ
Is it "affect change" or "effect change"?+
It is "effect change". Here effect is used in its rarer verb sense, meaning to bring about or accomplish. "To effect change" means to cause change to happen. "To affect change" would mean to influence some change that already exists, which is rarely what writers intend, so the standard phrase is effect change.
How do I remember which is which?+
Use the RAVEN mnemonic: Remember, Affect is a Verb and Effect is a Noun. That captures the most common usage. A second trick: A for Action points to Affect the verb, and E for End result points to Effect the noun. Both rules hold for ordinary writing; only the psychology and "to effect" exceptions break them.
Which is correct: "side effect" or "side affect"?+
It is "side effect". A side effect is a secondary result or consequence, so it takes the noun effect. You can test it by adding an article: "a side effect" works, but "a side affect" does not, because affect is normally a verb and cannot follow "a" in that phrase.
Going deeper
