The words may and might are very similar words, and they do not really have much grammatical difference. Most times, you can use the word may for might, and also use the word might for may. There will be no grammatical mistakes in doing such in most sentences, though there are exemptions. Actually, the word may is the present tense form, while it might is the past tense form. Still, you can use them for each other in most cases. One major exemption where you can use these words interchangeably is when you are asking questions. It will most likely be wrong, asking a question starting with the word 'might.'
For example, it would be wrong to say, "might I have a talk with you?" Instead, it would be correct to say, "May I have a talk with you?" Hence, when it comes to asking questions, you are meant to use the word "may," which will definitely be correct.