Verbs are also classified according to function. Action verbs show action or possession. Action verbs are either transitive or intransitive. Linking verbs show the condition of the subject. Auxiliary verbs, also called helping verbs, are used with other verbs to change the tense, voice, or condition of the verb.
Conditional verbs are verbs conjugated with could, would, or should to show a possible condition. They may be in any tense.
The principal parts of a verb are the four forms of the verb from which all forms of the verb can be made. In English the four principal parts are the present (or infinitive), the past tense, the past participle, and the present participle. Since the present participle is always formed the same way (add -ing), some lists of principal parts omit it.
One of the most important things about verbs is their relationship to time. Verbs tell if something has already happened, if it will happen later, or if it is happening now. For things happening now, we use the present tense of a verb; for something that has already happened, we use the past tense; and for something that will happen later, we use the future tense. Some examples of verbs in each tense are in the chart below: