Affect and effect are often used incorrectly, particularly in student essays. In most contexts, affect is a verb and effect is a noun. When you affect something, it produces an effect – and I think that is where some of the confusion stems from.
Affect as a verb means ‘to influence or change’ or ‘to make a difference to’, and it is the most common use of affect.
The new rules will affect thousands of people.
It can sometimes mean ‘to pretend’ or ‘to take on or adopt something pretentiously’.
I affected a happy disposition. He was known to affect an American accent.
It has limited usage (usually related to psychology) as noun referring to an emotion or feeling.
His reaction displayed a happy affect.
Effect as a verb means ‘to do’ or ‘to bring about’.
I will effect change.
But the most common usage of effect is as a noun meaning ‘a result’.
It had an immediate effect.
The a, an or the test
If you struggle to work out which word you need to use, this simple test might help. Does a, an or the appear in front of it? Or if you inserted a, an or the would the sentence make sense?
The effect was insignificant. It could
anaffect your lifestyle.
If the answer is yes, you probably need effect (the noun). If the answer is no, you probably need affect (the verb).