May and might

May is used to indicate permission ("May I have a word with you?") or possibility ("That may be."), though in some dialects, the former use is often supplanted by can (see below), and the latter by might (which was originally its past tense), making this auxiliary rather uncommon in those dialects.

May can be used with either a present or a future sense: "I'm not sure whether he's there now; he may not be, but even if he isn't, he may go there later." Theoretically speaking, might is the corresponding past-tense form, but since some dialects use might quite commonly with a present or future sense, it is more common to use may or might with the perfect aspect to provide a past sense: "He might have been gone when we got there, or he might have been hiding."

May is also used to express irrelevance in spite of certain or likely truth: "He may be taller than I am, but he's certainly not stronger" may means roughly, "While it's true that he's taller than I am, that doesn't make a difference, as he's certainly not stronger." (However, it may also mean, "I'm not sure whether he's taller than I am, but I am sure that he's not stronger.") In many dialects, might is used in this sense as well.

In addition to what has already been mentioned, might also serves as the conditional mood of may: "If he were more polite, he might be better liked." Also, while there are some dialects where the use of might to replace may is very common, even in colloquial or informal speech, there are other dialects where might serves a more polite or formal form of may, just as would does for will (see above) and could does for can (see below).