Is there an easy way to remember when to use the word affect or effect in a sentence? It is very confusing, and I still get them mixed up.
Ask yourself the question, did the object already exist before the effecting or affecting? If it did not, use effect; if it did, use affect.
Effect comes from Latin efficere, from ex-, "out", and facere, "to cause/make/do". When you effect something, you cause something to exist that didn't exist before: first it was in the darkness of nothingness, then it comes "out" into the world of reality. Notice the parallel to ex- in exist.
Affect comes from Latin afficere, from ad-, "to, in addition", and facere. When you affect something, you cause something to happen to a thing that already existed; you do something to it in addition to the fact that it already exists.
I forget where I originally got this from, but this humorous comment has helped me in the past...
Most of the time effect is a noun and affect is a verb.
If you're unsure, try substituting a different verb and see if it works.
As a child, he was affected by his parents.
As a child, he was
affectedeaten by his parents.
A verb works here so you should use "affected".
Cerberus did well to focus on AFFECT and EFFECT as verbs. While both are also used as nouns, most usage errors that I've seen involve their use as verbs. For example, do we say that attitude and planning affect outcome, or do we say that attitude and planning effect outcome? Do we say that our spending habits affect our ability to save for retirement, or do they effect our ability to save? Does bright light affect the eyes, or does it effect them. Does burning coal affect, or does it effect, carbon dioxide levels in the earth's atmosphere?
In each of the above cases, the correct choice is AFFECT. AFFECT, when used as a verb, commonly means "to influence." Note that when we say that X affects or influences Y, we're not providing the reader with information about the nature of the influence -- whether it's positive or negative, for instance. In the last example above, were not saying whether burning coal raises, or lowers, carbon dioxide levels. Nor are we asserting whether that influence is slight, significant, weak, or decisive.
On the other hand, if we want to assert that a particular action or condition will reliably produce a particular result, then the correct choice is EFFECT. For example, we would say that exposing the eye to bright light effects the contraction of the pupil (bright light causes contraction of the pupil). Or we might assert that the hallmark of an effective political leader is that she or he is capable of effecting needed reforms. EFFECT, when used as a verb, means "to bring about; produce as a result; cause; accomplish" (Webster's New World College Dictionary, Fourth Edition).
You might have noticed that the examples I gave above for using AFFECT as a verb are quite familiar to you, whereas the examples I gave for using EFFECT as a verb were not. If that is the case for you, then you can use AFFECT whenever you're not sure, and you'll usually be right. Hence the advice given by others to use AFFECT when it's a verb, and EFFECT when it's a noun.
One more observation: When I started using MicroSoft Word (R) many years ago, the spell checker would respond to "It seems like everything I do affects what other people think of me?" by asking me if I meant to use "effect." At first, I ignored it, then I started doubting whether I was using the right word. After the second or third time, I tried changing it to "effect," then asked the spell checker to recheck my work. It came back with
"did you mean 'affect'?" !! Then I realized what was going on: The spell checker DIDN'T KNOW which was correct, but it wouldn't admit that it didn't know! Instead it would ask me if perhaps I should be using the other one. So I suspect that much of the confusion prevalent today regarding affect vs effect can be laid at the feet of -- you guessed it -- Bill Gates. Thanks, Bill.