Generally "affect" is the verb and "effect" the noun. But since this is English, there has to be an exception. :D "Effect" as a verb means "to bring about; accomplish." And there're a couple of things with "affect" as well. My usual go-to source for grammar when I have a question: http://andromeda.rutgers.edu/~jlynch/Writing/index.html (http://andromeda.rutgers.edu/~jlynch/Writing/index.html)

So...

The weather affects my mood.

Although I usually have trouble with Mexican food, tonight I suffered no ill effects from my taco platter dinner.

Despite all my arguments, I could not effect a change in the administration's policy.


Sorry - I have trouble with short answers, but I just love grammar!