Affect is almost always a verb meaning to influence or to produce a change in something. Effect is almost always a noun meaning a result or a consequence. The fastest test: if you can swap in influence, you want the verb affect; if you can put the, an, or this in front of the word, you want the noun effect. For example: Poor sleep affects your focus, and the effect can last all day.
Most affect/effect decisions come down to a single question — do you need a verb or a noun?
Notice how the same situation can use both words: something affects something else (the verb, the action), and the effect is what you are left with (the noun, the outcome). The action comes first; the effect is the end result — which is exactly why affect and effect so often turn up in the same sentence.
Two substitution tricks settle almost every case:
Seeing the two words side by side in real sentences is the quickest way to lock in the difference.
A reliable pattern hides in there: the verb affect usually sits right next to its object (affect everyone, affect sales), while the noun effect is usually introduced by a little word such as an, the, this, no, or side, and is often followed by on (an effect on, no effect on).
The classic mnemonic is RAVEN: Remember — Affect Verb, Effect Noun. Hold on to just that and you will get the overwhelming majority of cases right.
A second cue: affect begins with a, the same letter as action — affect is the action that does something. Effect begins with e, and an effect is the end result. Action first, end result second.
Both words can cross over into the other part of speech. These uses are genuine and correct — they are simply far less common, which is precisely why they catch people out.
Used as a verb, effect means to bring something about, to cause it to happen, or to accomplish it. It is a step stronger than affect: to affect something is to change a thing that already exists, whereas to effect something is to make it happen in the first place.
This is the source of the notorious phrase effect change. To effect change means to bring change into being — and that is usually what people mean, so effect (not affect) is the right choice. Compare The protest affected government policy (it influenced policy that already existed) with The protest effected a change in policy (it produced a new one). If you are unsure, try swapping in bring about; if it fits, use effect.
There is a second, older sense of the verb affect: to pretend to have a feeling or quality, or to adopt a manner for show.
The related noun is affectation (a pretentious, artificial manner), and the adjective affected can mean insincere or put-on, as in an affected laugh.
In psychology and psychiatry, affect is a noun meaning a person's observable emotion or mood — the outward display of feeling. Unusually, it is stressed on the first syllable (AFF-ect) rather than the second.
Unless you are writing about mental health, you will almost never need this one — but it is the reason a spell-checker will not flag affect when it is used as a noun.
The adjectives cause their own trouble. Effective (from effect) means producing a result or working well: an effective treatment, an effective leader. Affective (from the psychological affect) means relating to emotions and moods, as in affective disorder or seasonal affective disorder. Nine times out of ten, the word you actually want is effective.
A handful of fixed expressions cause repeat mistakes. Here is the correct word in each:
No — and it is worth saying plainly, because plenty of word pairs do split along transatlantic lines (practice/practise, licence/license, -ise/-ize endings). Affect and effect are not among them. The spelling, the meanings, and the verb/noun split are identical in American, British, Australian, and every other variety of English. Learn the rule once and it travels everywhere.
For everyday writing, remember RAVEN: affect is the verb (to influence), effect is the noun (the result). Reach for the exceptions only when you mean to effect (bring about) something, to affect (feign) a manner, or to describe a person's affect in the clinical sense. Test yourself with two swaps — influence points to affect, and putting the or an in front points to effect — and you will rarely go wrong.
Affect is usually a verb meaning to influence or change something, as in: the noise affected my concentration. Effect is usually a noun meaning the result of a change, as in: the noise had a bad effect on my concentration. Put simply, affect is the action and effect is the outcome that follows it.
You effect change. Here effect is a verb meaning to bring about, so to effect change is to make it happen. Affect change is almost always a mistake, unless you specifically mean to influence a change that is already under way. When in doubt, swap in bring about; it fits effect, not affect.
It is affects me. When something influences you or has an impact on you, you need the verb affect: loud music affects me; the cold does not affect me. Effects me is incorrect in this sense. You would only use effect as a verb in set phrases like effect a rescue or effect a cure.
Yes. As a verb, effect means to bring about, cause, or accomplish something: the manager effected major changes; doctors effected a cure. It is far less common than the noun effect and easy to muddle with affect, but it is fully correct. Test it by swapping in bring about; if that fits, use effect.
In psychology, affect is a noun, stressed on the first syllable (AFF-ect), meaning a person's observable emotion or mood: the outward expression of feeling. Clinicians describe a flat affect, showing little emotion, or a bright affect. It is a specialist term; in everyday writing, affect is a verb, not a noun.
