Complement:

A complement tells us something about the nature of the subject or object.

Note: compliment can be a noun, a noun phrase, adjective, pronoun, or a number.

1.He is healthy.

   sub    adj com

2.He is the chairman.

   sub          N com

3.X.y.z is a popular center.

   sub          N.phrase comp

4.This book is hers.

            Sub      P.comp

5.X.y.z will be 5 years old on  2nd May.

    sub              No.comp