Modal verbs and its types

from here

Modal verbs or modal auxiliary verbs are a type of verbs that indicates modality,
i.e., likelihood, permission, ability and obligation.
Some of the common modal verbs are can, could, may, might and must. Let us understand them briefly.

Remember as a kid you asked your parents before going out to play,
“Can I go out to play?” Now, at your work place when you want to leave early, you have to ask for permission,
“Could I go home early today?”