'Affect' and 'effect' are among the easiest words in the English language to mix up in both speech and writing, because they sound so similar and are sometimes used in similar ways. Here is a helpful guide to help you avoid this confusion.
'Affect' is usually a verb, meaning to impact, change, or cause to happen. A good way of remembering this is to imagine that the 'a' in 'affect' stands for 'action', so it must be a verb.
In the above sentence, we can see that Jack is not his usual self. The death of his wife has both changed him and had a significant emotional impact on him. The use of 'affected' expresses that.
Generally speaking, if you can substitute 'affect' with another verb and still keep your intended meaning, then you know you have used it correctly.
'Effect' is usually a noun, and describes the result or consequence of a change or something being done. As it is often used when the end result of something is being discussed, a good way of remembering its correct usage is to imagine that the first letter ('e'), stands for 'end result'.
In all of the above sentences, 'effect' is a noun, and is used as a synonym of 'result' or 'consequence'. It is a general rule that if you can substitute 'effect' for 'result' and still keep your intended meaning, then you are using it correctly.
While almost always a noun, 'effect' can sometimes be used as a verb in the sense of bringing something about or accomplishing something. However, in that context it tends to be used in a particularly formal manner rather than in everyday conversation.
So, in summary, something must 'affect' something to produce an 'effect'. In other words, if something 'affects' you, you will feel the 'effect' of the change or impact it makes.
To avoid mistakes, keep in mind whether you are expressing action or talking about an event that has caused change. Here is an example of both words being used correctly in a sentence: