Difference between may, could, and can?

Question

I know that "can" means is someone able to do somehing, and "may" means they are allowed to do something. But what does "could" mean? What differs it from the other two?

For example:

"Can" you go?

"May" you go?

"Could" you go?

Answer 1

could is the past tense of can wherein may got also might as its past tense.

these are auxiliary verbs

Answer 2

Could is the ability to do something while may is the permission to do so.

Answer 3

All the three words are interelated ...but different with respect to tenses.

Can - Present Tense

Could - Past tense

May - Future Tense !

Answer 4

can u go.... telling u to leave...angry statement (can u go now)

may u go... asking politely to leave (u may go please)

could u go.... asking if u r able to leave for a certain purpose