The English words affect and effect are often confused by native speakers - don't let their mistakes affect your English.
Affect is a verb with several different meanings.
1. To have an influence on, contribute to a change in
What you do affects all of usThis decision will affect the outcome of the electionsInflation is affected by natural disasters
2. To touch, move; to act on the emotions of
I was profoundly affected by this movieHis actions were not affected by her pleas
3. To simulate
He likes to affect a British accentShe always affected her eccentricity
In psychology, affect is a noun which refers to a "feeling" or "emotion":
Your son's lack of affect explains why you find it difficult to gauge his moods.
Effect is most commonly used as a noun, and has three meanings.
1. Result, something brought about by someone or something
What was the effect of her decision?Side effects include nausea and fatigueI don't think it will have any effect on the outcomeThe law will go into effect tomorrowYou can clearly see the cause and effect
2. Something that gives the impression/sense of something else
The special effects were amazingMirrors will give the effect of a larger spaceHe said that just for effect
3. Effects can refer to belongings
Did you bring any personal effects?
As a verb, to effect means "to bring about, lead to a result"
The only way to effect change is to participateWhat is the best way to effect these improvements?This should effect a whole new way of thinking about it
The Bottom Line
The confusion between affect and effect comes out of the fact that affecting something leads to an effect. The two questions "How were you affected?" and "What was the effect on you?" mean almost exactly the same thing.
When you want to use one of these words as a noun, the one you want is probably effect. When you want a verb, most of the time you want affect. Effect is used as a verb only when it has a direct object and only when you mean "to bring about, lead to."
The difference between to affect and to effect can be seen here:
To affect the results - To influence, have an impact on the results
To effect the results - To bring about, lead to the (desired) results
From: e Learn English Language - Online language learning with Laura K. Lawless