Affect and Effect are frequently used incorrectly because people don't realize the difference between the two words. In most common situations, affect is used as a verb and effect as a noun. However, both words have alternate meanings when used as different parts of speech.
edit Differences in Usage
In general, affect is a verb and effect is a noun. When X "affects" Y, it is said that X produces an "effect" on Y. In passive form, Y is "affected" by X.
edit Examples of Affect vs Effect
- Carbon di-oxide emissions affect the environment.
- The effect of global warming is that glaciers will melt and sea levels will rise.
- The 2008 Presidential elections in the United States were likely affected by the war in Iraq.
- Reducing the marketing budget will affect sales growth.
- Abuse during childhood may lead to violence in adulthood. This is just cause and effect.
- We know the new marketing campaign is really effective because sales are up 350%.
- Do you know the side effects of Advil vs Tylenol?
- Doctors must keep in mind that X-Rays in CAT Scans may affect the body adversely on repeated exposure.
As a rule of thumb that works in most common usage scenarios, it is advisable to use affect as a verb (transitive, intransitive, active, passive) and effect when used as a noun.
edit Video explaining the difference
edit Usage in special cases
Like many other words in the English language, affect and effect have more than one meaning.
edit Affect as a noun
When used as a noun, "affect" means Feelings and desires as factors in thought or conduct or, more simply, external display of one's emotion or mood. The pronunciation of the word "affect" is slightly different when used as a noun. It is pronounced æf?kt. For example, John seemed completely devoid of affect., which means John did not display any emotions.
edit Effect as a verb
When used as a verb, "effect" means to execute, produce, or accomplish something. It is pronounced the same way whether used as a verb or a noun. For example, The best way to effect change in society is to work at the grassroots level. Here "to effect change" means "to produce change".
edit Effects as a plural noun
The word "effects" can also be used to mean "a person's belongings". For example, He left without any of his personal effects.