Confusable words

affect vs effect: what's the difference?

affect
verb
vs
effect
noun
? ?

Affect and effect are the single most confused word pair in English, mostly because they sound almost identical. The short version: affect is almost always a verb, effect is almost always a noun.

Affect

verb

To affect something is to change it or influence it in some way.

  • The noise outside affected his concentration.
  • Poor sleep can affect your mood the next day.

Effect

noun

An effect is the result of something, the change that was caused.

  • The medicine had an unexpected effect on her energy levels.
  • Climate change has a serious effect on coastal cities.

Side by side

affect effect
Part of speech Verb (almost always) Noun (almost always)
What it does Causes a change Is the result of a change
Simple test "It affected me" means it changed me "It had an effect on me" means it caused a change in me

Quick rule

Affect is the action, effect is the result. If you can put "the" or "an" in front of it, you probably want effect.

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