'Affect' is the verb meaning to influence something; 'effect' is the noun meaning result or consequence.
This is the verb: it means to have an influence or impact on something or someone. When something changes because of something else, that is "affect".
The new policy will affect everyone in the department.
Stress can significantly affect your ability to concentrate.
How will the merger affect the existing team structure?
This is the noun: it means the result or outcome of a cause. In very formal contexts it can also be a verb meaning to bring something about: "to effect change".
The effects of sleep deprivation become visible within days.
The medication had no noticeable effect on the symptoms.
Sound effects in film create powerful emotional responses.
Common mistake
Trick to remember it
Quick rule
"Affect" = to influence (verb). "Effect" = the result of that influence (noun). This rule works in 95% of cases.
Did you know?
Both words entered English from Latin in the 14th century: "afficere" (to influence) gave "affect", and "effectus" (result) gave "effect". There is a secondary use where "effect" can be a verb (to effect change = to bring about change) and "affect" is a noun in psychology (flat affect), but those are specialized cases, the basic rule covers 99% of real-life situations.
Exercise 1 · Pick the right one
What _____ did the cold weather have on the harvest this year?
Exercise 2 · Pick the right one
Lack of sleep can really _____ your concentration.
Exercise 3 · Form the word
One means to receive or agree to something, the other means to exclude or not include.
'Advice' is the guidance you receive (noun); 'advise' is the act of giving that guidance (verb).
'Aisle' is the walkway between rows of seats or shelves; 'isle' is a small island.
'Allowed' is the past tense of 'allow' (to permit); 'aloud' means making an audible sound.
Bryan López
Founder of SpeakUP Academy