Possibility: may and might
Both may and might are used to express a medium level of possibility. When may and might are used to express possibility in the present or future, their meaning is the same, but may has a slightly more formal sound. Might is slightly more common in everyday American English:
Nancy might drop in tonight.
Nancy might drop in tonight.
Nancy may drop in tonight.
The speaker believes that the possibility that Nancy will drop in and the possibility that she will not drop in are approximately equal.
The speaker believes that the possibility that Nancy will drop in and the possibility that she will not drop in are approximately equal.
Requests: may and might
Both may and might are used to make requests. May has a formal sound, and is less common than might. Can is the most common in American English:
most common: Can I drop in tonight?
most common: Can I drop in tonight?
formal: May I drop in tonight?
very rare: Might I drop in tonight?
Permission: may and can
May and can are also used to give permission. In this case, may is much more formal and is much less common than can. Might is not used for this purpose:
You can drop in after dinner.
You can drop in after dinner.
You may drop in after dinner.
