"effect" as a noun means "result", but as a verb, it means "to cause" or "to bring about". For example, "the invasion of Iraq effected a regime change" is also correct because the invasion brought about the regime change.

The subtle differences between the verbs "influencing" a change, and "causing" a change, can add to the difficulty of using affect/effect correctly.

And it gets worse, because "affect" can be a noun, too, meaning "a subjective feeling (not visible)": "He carried the affect of a man who had only witnessed an unjust killing and yet somehow felt responsible for it."

It can also be yet another verb, meaning "to feign" or "to pretend": "He would affect an interest in the homely rich girl as a tactic to increase his own wealth."

To summarize...

Common uses:

"to Affect", a verb, meaning, "to influence".
"Effect", a noun, meaning, "a result".

Occasional uses:

"to Effect", a verb, meaning, "to cause" or "to bring about".

Rare uses:

"Affect", a noun, meaning, "a (usually invisible) subjective feeling".
"to Affect", a verb, meaning, "to feign" or "to pretend".

And then there are the common catch phrases that have further new meanings:

"in effect" (in substance [but not literal reality])

"to the effect that" (having the meaning of [but not literally stated])

"personal effects" (personal goods or properties).

Unlike me, most people don't have the time to keep all that crap straight!