A predicate nominative is a noun, pronoun or other nominal that follows a linking verb and identifies or refers to the subject of the verb. It helps to provide information about the subject in some way. It describes or renames the subject of the sentence.
The predicate nominative answers questions of what or who, and it is used with linking verbs such as "to be" and all its forms. The linking verb serves as something like an equal sign so that what is on one side is similar to what is on the other side. After switching the subject of the sentence with the predicate nominative, the sentence should still make sense. In formal English, pronouns that serve as predicate nominatives are often in subjective case. The contemporary term for a predicate nominative is subject complement.
A predicate nominative differs from an object because it does not introduce a new participant to the sentence. Instead, it completes the sentence by adding information about the subject it refers to. For example, in the statement, "Ann Wright is my mother," Ann Wright is the subject of the sentence. The predicate nominative is the word "mother" because it identifies and provides information about the subject.