Affect and Effect

Most often, 'affect' is a verb and 'effect' is a noun. When 'affect' is used as a verb it means "to act on something and cause a change." When 'effect' is used as a noun it means "a change that results when something is done." Below are some examples of each word:

• The bad weather will affect our ability to drive.
• Our house wasn't affected by the power outage.
• He hopes the new management will have a positive effect on customer satisfaction.
• What effect does the medicine have on the heart?
• The children were studying cause and effect in science.
• We kept the problem from affecting our friendship.

Sometimes 'effect' is used as a verb to mean "to cause something to happen." It is often used in the phrase "to effect change."

• The activists hoped to effect positive social change in their community.

Less commonly 'affect' is used as a noun to mean "the facial expressions that go along with an emotion."

• The girl has a surprisingly flat [=emotionless] affect even when she's happy.

Most often when you see 'affect' it is a verb, and most often when you see 'effect' it is a noun.

I hope this helps.