A verb is the part of speech (or word class) that describes an action or occurrence or indicates a state of being. There are two main classes of verbs: (1) the large open class of lexical verbs (also known as main verbs or full verbs--that is, verbs that aren't dependent on other verbs); and (2) the small closed class of auxiliary verbs (also called helping verbs). The two subtypes of auxiliaries are the primary auxiliaries (be, have, and do), which can also act as lexical verbs, and the modal auxiliaries (can, could, may, might, must, ought, shall, should, will, and would). Verbs and verb phrases usually function as predicates. They can display differences in tense, mood, aspect, number, person, and voice.
