Affect is usually a verb that means “to influence or change something.” Effect is usually a noun that means “the result of a change.” If you can put the or an in front of it, you almost certainly want effect. If it’s something one thing does to another, you want affect.
- The cold weather affected my mood. (verb: it did something)
- The cold weather had an effect on my mood. (noun: the result)
That one rule handles the vast majority of sentences you will ever write. The rest of this post covers the two exceptions, the phrases that cause the most second-guessing, and a short practice set so the rule sticks.
The Default Rule: Affect Is a Verb, Effect Is a Noun
Think of it as cause and result. Affect is the cause in action. Effect is what you see afterward.
| Word | Usual part of speech | Meaning | Example |
|---|---|---|---|
| affect | verb | to influence, to change | Rain can affect traffic. |
| effect | noun | a result, an outcome | Rain has a big effect on traffic. |
A few more pairs to show the pattern:
- Caffeine affects sleep. / Caffeine has an effect on sleep.
- How will the new policy affect remote workers? / What effect will the new policy have on remote workers?
- The noise didn’t affect her concentration. / The noise had no effect on her concentration.
Notice the giveaway words around effect: an effect, the effect, no effect, a big effect, side effects. Articles and adjectives attach to nouns, so they point you straight to effect.
Quick rule: If the word follows a, an, the, or an adjective, use effect. If it describes what something does to something else, use affect.
Memory Tricks That Actually Work
RAVEN
The most popular trick is the acronym RAVEN:
- Remember
- Affect is a
- Verb,
- Effect is a
- Noun
Memory trick: RAVEN = Remember, Affect Verb, Effect Noun.
A comes before E
In the alphabet, A comes before E. In real life, an action (affect) comes before its result (effect). You affect something first; the effect shows up later.
The “arrow” test
Picture affect as an arrow pointing at something: The storm → affected → the flight. If your sentence has that shape (something acting on something else), affect fits.
Exception 1: “Effect” as a Verb
Effect can be a verb, but it means something different from affect. As a verb, effect means “to bring about” or “to cause something to happen.” It usually appears with words like change, reform, or a cure.
- The new manager effected real change in the department. (She brought about change.)
- Activists worked for years to effect reform.
Compare these two sentences, because the difference matters:
| Sentence | Meaning |
|---|---|
| The CEO affected change. | The CEO influenced some change that was already happening. |
| The CEO effected change. | The CEO made the change happen. |
In almost every case, writers mean the second one: effect change. If you’re tempted to write “affect change,” pause and ask whether you mean “bring about change.” If so, use effect.
That said, verb effect is fairly formal. In everyday writing, “made changes” or “brought about change” often sounds more natural.
Exception 2: “Affect” as a Noun
Affect can also be a noun, but mostly in psychology and medicine. There, affect (stressed on the first syllable: AF-fect) means a person’s observable emotional expression, such as their facial expressions, tone, and body language.
- The patient showed a flat affect during the interview.
- Her affect brightened when her family arrived.
Unless you’re writing a clinical report or a psychology paper, you will rarely need noun affect. If you’re writing about results or outcomes, the noun you want is effect.
A bonus meaning: “affect” as “to pretend”
Affect has one more verb meaning: to put on a manner or style that isn’t natural to you. This is where the adjective affected (meaning “artificial” or “showy”) comes from.
- He affected a British accent after one semester abroad.
- Her laugh sounded affected and forced.
Tricky Phrases: Which Spelling Do They Use?
Some fixed phrases cause trouble because they don’t match the cause-and-result idea at first glance. Here are the ones people ask about most.
| ❌ Avoid | ✅ Use | Why |
|---|---|---|
| The rule takes affect Monday. | The rule takes effect Monday. | “Take effect” = become active; effect is a noun here. |
| The ban is in affect. | The ban is in effect. | “In effect” = in force, active. |
| Possible side affects include nausea. | Possible side effects include nausea. | Side effects are results. |
| We were all effected by the news. | We were all affected by the news. | The news acted on us; that’s a verb. |
| The changes went into affect. | The changes went into effect. | “Go into effect,” like “take effect.” |
| He said it to great affect. | He said it to great effect. | “To great effect” = with a strong result. |
“Affected by” vs. “effected by”
This is the trap that catches careful writers. “Affected by” is the one you want almost every time:
- Thousands of residents were affected by the flooding.
- The schedule was affected by the holiday.
“Effected by” is correct only when you mean “brought about by”: The merger was effected by a team of lawyers (the lawyers made the merger happen). That’s rare. When in doubt, choose affected by.
“In effect” as “essentially”
In effect also means “basically” or “in practice”: By skipping the meeting, he was, in effect, turning down the offer. Same spelling, still effect.
Affect and Effect in Different Forms
The rule still applies when the words change shape.
- Affecting (adjective from the verb): The song was deeply affecting. (It moved people emotionally.)
- Effective (adjective from effect): The new filter is very effective. (It produces results.)
- Effectively (adverb): She effectively ran the whole project.
- Unaffected (adjective): The rural roads were unaffected by the snow.
If you remember that effective comes from effect (results), you’ll never write “affective solution” when you mean one that works. (Affective is a real word, but it’s another psychology term meaning “related to emotions,” as in affective disorders.)
For more word pairs that sound alike but act differently, browse our guide to tricky words.
Practice: Affect or Effect?
Fill in each blank with affect, affects, affected, effect, or effects.
- The medication has a few mild side ______.
- Bad weather can ______ your flight schedule.
- The new speed limit takes ______ on January 1.
- Everyone in the office was ______ by the power outage.
- The committee hopes to ______ lasting change in the school system.
- Lack of sleep had a noticeable ______ on his performance.
Answer Key
- effects (noun: results of the medication)
- affect (verb: weather influences the schedule)
- effect (fixed phrase: “takes effect”)
- affected (verb: the outage acted on everyone)
- effect (verb meaning “bring about”: effect change)
- effect (noun, after “a noticeable”)
If you got number 5, you’ve mastered the hardest part. If you’d like to keep practicing similar puzzles, try who vs. whom next, or brush up on parts of speech in our grammar rules guide, since knowing verbs from nouns is what makes this pair easy.
Quick Reference
| If you mean… | Use | Example |
|---|---|---|
| to influence | affect (verb) | Stress can affect your health. |
| a result | effect (noun) | Stress has an effect on your health. |
| to bring about | effect (verb) | They effected a major change. |
| emotional expression (psychology) | affect (noun) | The patient had a flat affect. |
| to fake or put on | affect (verb) | He affected a casual tone. |
The Bottom Line
In everyday American English, affect is the verb and effect is the noun. Use affect when something influences something else, and effect when you’re talking about the result. Watch for the two exceptions: effect change (bring about) and the psychology noun affect. And remember the fixed phrases: take effect, in effect, side effects, and affected by.
Keep RAVEN in your back pocket, and you’ll get this right every time. For more quick, practical fixes like this one, explore the rest of GrammarVista.com USA, starting with our tricky words guide.