A part of sentence that gives more information about the subject, or, in some other structures, about the object.
Some clauses consist of a subject, the verb be, and an expression that describes the subject.
She was the first person to arrive.
He looked tired.
She is a journalist.
They were very excited.
The milk turned sour.
The expression that describes the subject in clauses like these is often called a subject complement. Subject complements can follow not only be, but also other copular verbs like look, seem, turn and become.
An object complement is a phrase which follows a direct object and either modifies that object or denotes something identical to it.
They elected him their leader.
The jury found him guilty.
He called me a liar.
God called the light day.
You make me nervous.
Words and expressions that complete the meaning of a noun, verb, preposition or adjective are also called complements.
I am interested in learning to fly.
She is fond of ice cream.
The cat is on the roof.
Let us get a bottle of wine.