Can is an auxiliary verb, a modal auxiliary verb. We use can to:
Structure of Can
subject + can + main verb
The main verb is always the bare infinitive (infinitive without "to").
The main verb is always the bare infinitive (infinitive without "to"). We cannot say:
Use of Can
can: Possibility and Ability
We use can to talk about what is possible, what we are able or free to do:
Normally, we use can for the present. But it is possible to use can when we make present decisions about future ability.
can: Requests and Orders
We often use can in a question to ask somebody to do something. This is not a real question - we do not really want to know if the person is able to do something, we want them to do it! The use of can in this way is informal (mainly between friends and family):
We sometimes use can to ask or give permission for something:
(Note that we also use could, may, might for permission. The use of can for permission is informal.)