dear teachers,

i'm confusing about the usage of 'may' and 'might'.i have no idea how to use them correctly.
In most cases you can use them interchangeably: might is slightly more polite or diffident than may. Otherwise, might is the past tense of may.

The following remarks are for American English.

may and might are equivalent when they mean that something is possible.

It may rain today. / It might rain today.
Both mean
It is possible that it will rain today.

Susan may be late for the meeting. / Susan might be late for the meeting.
Both mean
It is possible that Susan will be late for the meeting.

might is more usual in ordinary conversation. may is more usual in writing, especially academic writing.

On the other hand, if you are asking permission, use can or may (usually with I). may is more formal and refined. Many people consider it more polite. But in most ordinary conversations, can is used.

Can I take this seat? / May I take this seat?
Can I buy you dinner? / May I buy you dinner?
Can I have your address? / May I have your address.

If you use might in these patterns, you are being very tentative, even timid. This formula with might is very rare in most ordinary conversations in the U.S.

In summary, in AmE you rarely need the word may, except for formal situations. Use might for possibility and can for permission.