Back when I was in grammar school during high school, I distinctly remember the difference in use between “may” and “might”. “May” was used to denote permission, as in “You may kiss the bride.” “Might,” on the other hand, was employed to indicate a possibility, as in “You might have a chance at the world title this year.”
That rule, at least back then, was pretty hard and fast. In fact, I remember it so well because I got chastised about using them interchangeably so many times. That’s why I found it so odd a few years ago when I started using a writing software and it wasn’t declaring my use of “may” to show possibility as an error.
Nowadays, the word “may”, as an auxiliary verb, is still widely used to denote permission. However, it is also employed as an auxiliary that indicates a likelihood or a possibility. “May”, after all, is the source word of “maybe”, a word that’s all about possibility. In the English language, “may” is always attached to a verb to show that the action can happen.
“Might,” on the other hand, is often treated as a slightly weaker form of “may”. The fact that “You might have a shot at this year’s tournament” is less likely (but is still a possibility) than the reality that “You may join the contest.”
As such, in most modern texts, “may” is used to imply a good probability for the action while “might” typically stands for a more unlike possibility. Both words can be used in either present or past tense, although some authors still prefer to use “might” when writing in the past tense.
Here’s an exception, though: when the sentence uses more than one verb, it’s usually best to use might in place of may. To illustrate this, check out this example: “I thought I might end this piece now.”