"Affect" is almost always a verb meaning to influence or change something ("The rain affected our plans"). "Effect" is almost always a noun meaning a result ("The rain had no effect on our plans"). A quick trick: A is for Action (affect = verb), E is for End result (effect = noun).
These two words trip up even confident writers because they sound almost identical and both relate to cause and consequence — but they play different grammatical roles almost all of the time.
The basic rule
- Affect is a verb. It means to influence, change, or have an impact on something. "Lack of sleep affects your concentration."
- Effect is a noun. It means a result or outcome. "Lack of sleep has a serious effect on your concentration."
A trick to remember it
Think: Affect = Action (a verb, something being done), Effect = End result (a noun, the thing that happened). If you can put "the" or "an" in front of the word, you almost certainly want "effect" — "the effect", "a side effect".
The exceptions (why this trips people up)
Both words have rarer opposite uses that catch people out:
- Effect can be a verb meaning "to bring about" or "to cause to happen" — usually in formal writing. "The new manager effected several changes to the schedule." Here it means she caused the changes to happen, not that she was influenced by them.
- Affect can be a noun in psychology, meaning a person's outward display of emotion. "The patient showed a flat affect." This is specialist usage — you're unlikely to need it outside clinical writing.
For everyday writing, the simple rule (affect = verb, effect = noun) is right about 95% of the time.
More examples
- "The medication may affect your appetite." (verb — influences)
- "The medication's effects include drowsiness." (noun — the results)
- "How will this policy affect small businesses?" (verb)
- "What effect will this policy have on small businesses?" (noun)
Frequently Asked Questions
Is it "affect my life" or "effect my life"?
"Affect my life" — you want the verb, since something is influencing your life. "Effect" would only fit if you meant a noun, e.g. "the effect on my life."
Can "effect" ever be a verb?
Yes, though rarely — "to effect" means to bring something about or cause it to happen, as in "effect change." It's formal and much less common than "effect" the noun.
What's an easy way to remember affect vs effect?
Affect = Action (verb). Effect = End result (noun). If you can put "the" or "an" before it, it's almost always "effect."