What's the Difference Between 'Affect' and 'Effect'?

The basic difference between "affect" and "effect" is pretty simple. One word has an influence, while the other has a result. "Affect," which is a verb, means "to impact, change or influence." "Effect," which is a noun, means "a result or consequence."

Take these sentences, for example, that use the two words "affect" and "effect:"

• When a cold weather system and a warm weather system collide, the effect may be high winds that have a devastating effect on your property.

• As I mentioned earlier, the weather could affect someone's mood.

• The earlier sunset will affect me personally, but not as much as my emotions affect me on a daily basis.

Makes sense, right? Truth is, there are several more key differences that can affect when you choose one word over the other.

Knowing the exceptions to these words could, in effect, influence whether you use the noun version or the verb as an action word.

Here are a few more key differences between the meaning of "affect" and "effect" that offer clues as to the correct usage of these words.

When "effect" is used as a noun meaning "a result or consequence," it will usually follow these words:

These sentences are examples of using "effect" correctly in its noun form:

• It will take time for the changes to have an effect, but they aren't likely to impact your personal effects.

• Scientists are studying the effect of gamma rays on bacteria.

• The workers on strike are eager for the policy change to take effect in writing.

"Affect," when used as a verb meaning to "influence someone or something," does not follow any of the words that "effect" does. When used properly, the verb "affect" never follows the words "the," "any," "an," "into," "on," "take" and "or."

The following sentences are examples of using "affect" as a verb:

• Road construction will affect everyone's mood, but so will the sun coming out.

• This new homeroom policy may affect student behavior.

• The new law is going to affect the cold weather we have because of climate change.

If you are one of the many people who struggle to remember the difference between writing "affect" and "effect" in a sentence, one trick is to look to the first letter of each word for a clue. The "a" in affect signals action, which could remind you to use it as a verb. When you see the "e" in effect, remember the phrase "cause and effect" — cause creates effect, which is the noun form of the word.

The usage of the verb "affect" versus the noun "effect" may seem straightforward, and it usually is — until it's time to break the rules for these words, that is. 

Like every other confusing aspect of the English language, there are rules and there are exceptions when using these two words. To get these two words right, even though they sound alike, the end result is that you must know the exceptions as well as the rules.

While the word "effect" is most often used in English as a noun to signify "a change that results when something is done or happens" or "a particular feeling or mood created by something," there is one notable exception.

The word "effect" sometimes can be used as a verb. For example, in the phrase "the new administration hopes to effect a peace settlement," the word "effect" is a verb meaning that it "caused something to come into being."

When "effect" is used as a verb, the verb version also may signal that something has been accomplished. For example, if "Professor Darling is determined to effect change," then the word "effect" is being used as a verb to show that something is potentially being accomplished and that she has been able to effect change. "Effect" as a verb will affect the way you use it.

These exceptions aren't new rules, but they can make it tricky to use the right words in the correct context when speaking or writing.

The exception in English to using "affect" as a noun is a fairly straightforward difference between "affect" and "effect," as far as exceptions go. There is really only one usage in which "affect" should be used as a noun instead of a verb.

The exception to using "affect" as a noun affects a narrow segment of options used when describing, speaking or writing about emotions or mood. Knowing this exception can help you know when to use "affect" as producing change and when to use it as a noun that represents an object.

For example, the noun "affect" becomes the right word to describe "an emotional response or impact."

This often is the case in psychology or psychiatry when the noun "affect" refers to an emotional response — for example, the gestures, body language, vocal tone or facial expressions that we produce as the consequence of specific emotions. 

The result of using "affect" as a noun is that this "affect" — usually referred to as "flat affect" — also commonly is used to describe a lack of response.

The following sentences are examples of using the noun "affect" as an object word:

• She did not have an emotional response to the sad movie; her affect was flat.

• His accent was an affect because he was only pretending to be French.

While knowing the difference between "affect" and "effect" when writing or speaking can take a bit of getting used to, knowing when to deploy the right word — and what the exceptions to the right word are — will help you make more sense of the English language.