Modal verb

Modal verbs modify a verb phrase to communicate shades of meaning, such as tense and obligation. Some modal verbs do nothing other than this; some have a life of their own and their own meaning, such 'do' or 'need'.

The future is expressed by a modal verb such as 'shall', 'will' or 'going to' (and also in other ways: see future tense).

Other modals express ideas of possibility ('can'), obligation ('should', 'must' etc) and possibility ('may', 'could') and so on. Some other examples are: 'dare', 'need', 'ought to', 'had better', 'have to', 'be able to', 'be obliged to', and 'be supposed to'.

There are several different classifications of modal verbs. These have less 'strength' as important features of grammar than the central modals and semi-auxiliaries in the examples above. Constructions like 'seem to', 'get [with the -ed participle]' and 'keep' [with the -ing participle]', etc, can be helpful for foreign learners to learn, and as examples of modality for native learners.