Affect | effect

Affect and effect are often confused because their meanings are so similar. Technically it works like this: affect (spelled with an 'a') is a verb, and effect (spelled with an 'e') is a noun (most of the time).

Affect

Affect verb meaning to influence.

The bully's nasty words affected her deeply.

I knew my sprained ankle would affect my ability to run the following day.

Here is an example from a more academic sentence:
Luck therefore, says Richards (1993, p. 171), does "affect deserts [ie. that which we deserve], but only ...[in]... recognizing that we are not omniscient about such matters, and that we must be responsible in our inferences about them".

Reference:

Richards, N. (1993). Luck and desert. In D. Statman (Ed.) Moral luck. New York, NY: SUNY Press

Effect is a noun meaning the result of.

The bully's nasty words had no effect on her.

The painkillers for my sprained ankle had an anti-inflammatory and calming effect.

Affect is sometimes used as a noun to represent the impact that a person's attitude can have on his or her ability to perform in a certain way. It might be used in an education context with reference to the emotional and external factors that influence a child's ability to learn, or as Artie explained in the first video, in psychology. (It is pronounced / 'ʌfekt / (uh-fect) - with the stress on the A).

In the Solomon Islands the impact of affect is significant with regards to widespread literacy under-achievement in primary schools.

In the Solomon Islands the impact of affect is significant with regards to widespread literacy under-achievement in primary schools.

Amnesty International hopes to effect change in third-world countries.

Both of these exceptions above are specialized (and infrequently applied) uses of these words and are not usually the reason that students get them muddled.