Affect and effect are two words that are commonly confused.
affect is usually a verb (action) - effect is usually a noun (thing)
Hint: If it's something you're going to do, use "affect." If it's something you've already done, use "effect."
To affect something or someone.
Meaning: to influence, act upon, or change something or someone.
For example: The noise outside affected my performance.
To have an effect on something or someone
!Note: effect is followed by the preposition on and preceded by an article (an, the)
Meaning: to have an impact on something or someone.
For example: His smile had a strange effect on me.
!Effect can also mean "the end result".
For example: The drug has many adverse side effects.