What is the difference between the words affect and effect?
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I think that many dictionaries include usage notes on these two words. For instance, the American Heritage Dictionary:

Usage Note:

Affect and effect have no senses in common. As a verb affect is most commonly used in the sense of "to influence" (how smoking affects health). Effect means "to bring about or execute": layoffs designed to effect savings. Thus the sentence These measures may affect savings could imply that the measures may reduce savings that have already been realized, whereas These measures may effect savings implies that the measures will cause new savings to come about.


In order to understand the correct situation in which to use the word affect or effect, the first thing one must do is have a clear understanding of what each word means. According to yourDictionary.com, the word Affect means:
  1. To have an influence on or affect a change in: Inflation affects the buying power of the dollar.
  2. To act on the emotions of; touch or move.
  3. To attack or infect, as a disease: Rheumatic fever can affect the heart.


The word effect has a different meaning. Here is the meaning according to yourDictionary.com:
  1. Something brought about by a cause or agent; a result.
  2. The power to produce an outcome or achieve a result; influence: The drug had an immediate effect on the pain. The government's action had no effect on the trade imbalance.
  3. A scientific law, hypothesis, or phenomenon: the photovoltaic effect. |
  4. Advantage; avail: used her words to great effect in influencing the jury.
  5. The condition of being in full force or execution: a new regulation that goes into effect tomorrow.
  6. Something that produces a specific impression or supports a general design or intention: The lighting effects emphasized the harsh atmosphere of the drama.
  7. A particular impression: large windows that gave an effect of spaciousness.
  8. Production of a desired impression: spent lavishly on dinner just for effect.
  9. The basic or general meaning; import: He said he was greatly worried, or words to that effect.

Grammar Rules for Affect and Effect

Now that we have the two definitions, how do we know which word to use? Here are a few suggestions to keep in mind:

1. If you are talking about a result, then use the word "effect."
  • Example: What effect did the loss have on the team?
2. It is appropriate to use the word "effect" if one of these words is used immediately before the word: into, on, take, the, any, an, or and.
  • Example: The prescribed medication had an effect on the patient's symptoms.
  • Example: In analyzing a situation, it is important to take the concepts of cause and effect into consideration.
3. If you want to describe something that was caused or brought about, the right word to use is effect.
  • Example: The new manager effected some positive changes in the office. (This means that the new manager caused some positive changes to take place in the office.)
4. Affect can be used as a noun to describe facial expression.
  • Example: The young man with schizophrenia had a flat affect.
  • Example: The woman took the news of her husband's sudden death with little affect.
5. Affect can also be used as a verb. Use it when trying to describe influencing someone or something rather than causing it.
  • Example: How does the crime rate affect hiring levels by local police forces?
  • Example: The weather conditions will affect the number of people who come to the county fair this year.
Students: Are you brave enough to let our tutors analyse your pronunciation?
Hey I am writing my personal statement and my tutor won't be able to review it so I was wondering if I am using the word 'effect' in the right context:

' One of the experiments that I undertook whilst at college was the production of aspirin. It really amazed me that such a small molecule is able to have such a profound effect on the body and it really made me determined to study a XXX degree.'

I really hope that you will be able to help me!

Thank you,
'. . .a profound effect. . .' is correct.
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ScottJacksonWhat is the difference between the words affect and effect?
See The difference between "effect" and "affect"