This terrible twosome is responsible for many of the errors I spot whilst proofreading. Affect is a verb, and therefore action is implied. Effect, however, is primarily used a noun. One way to remember the difference is that both affect and action start with “a”.
The medication was supposed to have side effects, so I waited to see how it would affect me.
I was greatly affected by my uncle’s death, and I was surprised to discover that he left me his personal effects in his will.
The new boss effected changed so quickly that it affected morale in the office. In this example, effect is used as a verb to mean “to cause something to happen”.
The special effects in the movie were quite effective; they made the scene more emotional and affecting.
Affect in particular can be used in different ways. In the preceding sentence, it is used in the sense of “inspiring emotion”. It can also be used to mean “to pretend”: The guests affected American accents for the Roaring 20s party.
To make sure you use affect and effect properly, always doublecheck this pair of homophones!