An intransitive verb is a type of verb that does not require a direct object to complete its 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 subject, the dog, is doing. Intransitive verbs can often be followed by adverbs or prepositional phrases that provide additional information. For instance, in the sentence "She runs quickly," the verb "runs" is intransitive, and "quickly" describes how she runs. Other examples include verbs like "sleep," "arrive," and "fall," which also do not take a direct object.