'''Affect''' (transitive verb):	to cause an effect upon
	'''Effect''' (transitive verb):	to bring into being, to cause
	'''Effect''' (noun):	something that inevitably follows an antecedent (as a cause or agent)

To affect something is to cause it to change in some way. To effect something it to cause it to come into being. Effecting a change affects the changed thing with an effect. What could be more clear?

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From Strunk, William, Jr. and White, ''The Elements of Style'', V. WORDS AND EXPRESSIONS COMMONLY MISUSED:

'''Effect.''' As noun, means ''result;'' as verb, means ''to bring about, accomplish'' (not to be confused with ''affect'', which means "to influence"). 

As noun, often loosely used in perfunctory writing about fashions, music, painting, and other arts: "an Oriental effect;" "effects in pale green;" "very delicate effects;" "broad effects;" "subtle effects;" "a charming effect was produced by." The writer who has a definite meaning to express will not take refuge in such vagueness. 

-- StevenNewton


'''Affect''' is also used as a noun in psychology, meaning, roughly, "reaction". "The patient received the bad news without affect."
"Flat affect" and "neutral affect" are fancy ways of saying "emotionless."