Affect and effect sound almost the same, look almost the same and are both connected to change. No wonder they are among the most confused words in English. The good news: one simple rule fixes the mistake about 95% of the time.
⚡ Quick answer
Affect is usually a verb: it means to influence something.
Effect is usually a noun: it means the result of a change.
Memory trick: Affect = Action, Effect = End result.
When to use affect
Use affect when something acts on or influences something else. It is an action word.
Lack of sleep can affect your concentration.
The storm affected flights across the country.
Her kind words deeply affected me.
When to use effect
Use effect when you mean the result or outcome. You can usually put “the” or “an” in front of it.
The medicine had an immediate effect.
The new policy will take effect next month.
Social media has a big effect on young people.
The tricky exceptions
Effect as a verb
In formal writing, effect can be a verb meaning “to bring about” or “to cause”. It is most common in the phrase “effect change”.
The new manager hopes to effect real change in the team.
Affect as a noun
In psychology, affect can be a noun meaning a person’s visible emotion. You will rarely need this in everyday writing.
The patient showed a flat affect during the session.
Affect vs effect at a glance
| Affect | Effect | |
|---|---|---|
| Usually | Verb | Noun |
| Meaning | To influence | A result |
| Example | Noise affects sleep. | Noise has an effect on sleep. |
| Trick | A = Action | E = End result |
Quick practice
Fill in the blank, then check your answers below.
- The cold weather will ___ the harvest.
- The movie had a strong ___ on the audience.
- How will this decision ___ our plans?
Answers: 1. affect, 2. effect, 3. affect.
Frequently Asked Questions
Is it “affected” or “effected”?
In most sentences it is “affected”, as in “I was affected by the news.” Use “effected” only when you mean “brought about”, as in “they effected a change.”
Is it “side affect” or “side effect”?
It is always side effect, because it is a result (a noun).
Final thoughts
Remember: Affect is the Action, Effect is the End result. Want to test yourself? Try our free spelling quiz and grammar checker.