Helping verbs have no meaning on their own. They are necessary for the grammatical structure of a sentence, but they do not tell us very much alone. We usually use helping verbs with main verbs. They "help" the main verb (which has the real meaning). There are only about 15 helping verbs in English, and we divide them into two basic groups:

1. Primary helping verbs (3 verbs) - These are the verbs be, do, and have. Note that we can use these three verbs as helping verbs or as main verbs.

2. Modal helping verbs (10 verbs) - We use modal helping verbs to "modify" the meaning of the main verb in some way. A modal helping verb expresses necessity or possibility, and changes the main verb in that sense.These are the modal verbs:
can, could / may, might / will, would, / shall, should / must / ought to