A verb is a type of word that refers to either an action or a state. Both "jump" and "be" are verbs, although they fall into different subcategories. Verbs are classified as either action verbs or linking verbs, main verbs or auxiliary verbs, transitive verbs or intransitive verbs and phrasal verbs.
The English words "jump," "wish," "read," "drink" and "commit" are all examples of action words. Such verbs modify their subject as performing an action. For instance, "he jumps," she wishes," "you read," "I drink" and "they commit."
Linking verbs include "is," "am," "are" and "be," among others, and are commonly used to connect a subject to an adjective. For example, if the subject is "you" and the adjective is "nice," the linking verb might be "are" or "be."
The difference between main and auxiliary verbs is that the main verb can be used alone within a sentence. "Jump," as in "you jump," needs no additional verb, whereas auxiliary verbs such as "have," "is" and "should" do, as in "you should jump."
Similarly, transitive verbs link subject and object, whereas intransitive verbs can be used alone. Many verbs can be used as transitive and intransitive, depending on the sentence in which they appear. For instance, "she reads" (intransitive) makes just as much sense as "she reads cereal packets" (transitive).
Finally, phrasal verbs are verbs whose meaning has been modified by the addition of another word. Examples include "read out," "drink up" and "stand up."