Intransitive verbs are action verbs that do not require a direct object to complete their meaning. This means that the action of the verb does not transfer to a noun or pronoun. For example, in the sentence "The dog barks," the verb "barks" does not act on anything; it simply describes what the dog is doing. Common examples of intransitive verbs include run, sleep, and arrive. These verbs can stand alone in a sentence without needing additional information. For instance, "She sleeps" is complete without specifying what she sleeps on or with, highlighting the self-contained nature of intransitive verbs.