You use may to indicate that something will possibly happen or be true in the future, but you cannot be certain.

You use may to indicate that there is a possibility that something is true, but you cannot be certain.

You use may to indicate that something is sometimes true or is true in some circumstances.

You use may have with a past participle when suggesting that it is possible that something happened or was true, or when giving a possible explanation for something.

You use may in statements where you are accepting the truth of a situation, but contrasting it with something that is more important.

You use may when you are mentioning a quality or fact about something that people can make use of if they want to.

You use may to indicate that someone is allowed to do something, usually because of a rule or law. You use may not to indicate that someone is not allowed to do something.

You use may when you are giving permission to someone to do something, or when asking for permission.

You use may when you are making polite requests.

You use may, usually in questions, when you are politely making suggestions or offering to do something.

You use may as a polite way of interrupting someone, asking a question, or introducing what you are going to say next.

You use may when you are mentioning the reaction or attitude that you think someone is likely to have to something you are about to say.

You use may in expressions such as I may add and I may say in order to emphasize a statement that you are making.

If you do something so that a particular thing may happen, you do it so that there is an opportunity for that thing to happen.

People sometimes use may to express hopes and wishes.