Affect means to influence or to produce a change in something.
The tornado affected citizens within forty miles of Topeka.
The medicine will affect your eyesight for at least an hour.
Winning the swimming medal affected Tina’s performance in school, too.
Here’s a mnemonic: A is for action. Verbs are about action. Affect starts with an A, so it’s a verb. Presto.
Effect is a noun, and it means the result of a change. So, if an event affects your life, you will feel the event’s effect.
The effect of the tornado was devastating.
You’ll feel the effect of the medication in the next twenty minutes.
Tina’s big win had an effect on her confidence level overall.
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