Where's Peter? He may be at school (= perhaps he is at school)
He might be in class (= perhaps he is in class)
We use may or might to say that something is a possibility. usually you can use both of them, although might suggests a weaker possibility.
He may be wrong / He might be wrong
The negative forms are may not and might not (mightn't).
He may not be wrong (=perhaps he is not wrong)
It might not be true (=perhaps it is not true)
Sometimes COULD has a similar meaning to "may" and "might".
The phone is ringing. It may/might/could be Tim
Study this example:
But couldn't is different from "may not" and "might not". Compare:
It may/might not be true (perhaps it is not true)
It couldn't be true ( it is not possible that it was true)
" May" and "might" are also used to talk about possible actions or happenings in the future.
I don't know where to go on holiday this summer. I may/might go to Malta ( perhaps I will go to Malta)
Tim might not / may not come to the exam tomorrow ( perhaps he will not come )