In English, sentences have a subject and a verb. The subject is the person or thing that is being described or is doing something. The verb is the action word like run or sing, or a word like am, is, or are that links the subject to a description. In Spanish, sentences also have a subject and a verb. Both English and Spanish use nouns as subjects. Nouns can be replaced with pronouns. The pronouns that can replace subjects in sentences of both English and Spanish are known as subject pronouns. In Spanish the subject or subject pronoun determines a specific form the verb takes, and these different forms constitute what in language is known as conjugation. Conjugation refers to the process of changing a verb form to provide information about the action being performed by the subject or subject pronoun. But the form any verb takes first is determined by the subject or subject pronoun. Below are the subject pronouns of English and Spanish.