A linking verb shows existence. We call it a linking verb because the verb links the subject to another word. In a sentence with a predicate adjective, the linking verb links the subject to an adjective that describes the subject. These sentences use an existence verb to link the subject to a predicate adjective:
Joe is athletic.
Mary is pretty.
Bob was sad last night.
My dog is hungry.
In each of these sentences, the linking verb connects the subject to an adjective that describes the subject.
I like to call these linking verbs equals verbs because the subject equals the describing word that follows the verb. Joe equals athletic. Mary equals pretty. Bob equals sad. My dog equals hungry. There is no action in these sentences. There is just a subject being equal to the adjective that describes the subject.
Use a linking verb to connect a subject to a describing word. We call an adjective linked to a subject by the linking verb a predicate adjective.
▶It’s your turn. Find the predicate adjective in this sentence: Jim’s house is big. Did you figure it out? Good for you!