Affect vs. Effect

In their most common usages, affect is a verb meaning “to influence” or “to have an impact on,” while effect is a noun meaning “result, consequence, outcome”:

affect the outcome
affected by the weather

the war’s effects
the effect of the decision

However, effect can also be a verb when it is used to mean to bring about or to put into effect:

“to effect a change” = “to bring about a change” (not “to influence a change”)
effect a solution to the problem

Affect has other less common uses as well: one can “affect a Cockney accent” or “affect a limp” (meaning “to feign; to give the appearance of; to adopt artificially”), and in psychology, an affect (pronounced “A fect,” not “uh FECT”) is “the subjective aspect of an emotion.” These definitions are not likely to be tested on standardized tests like the SAT, ACT, and TOEFL, but it’s good to be aware of them.