The pronoun antecedent is the noun that the pronoun replaces. The noun either precedes the pronoun in the same sentence, a previous sentence, or is known to the speaker and those spoken to.

For example:

"When George got to 19th Street, he got off the train." "George" is the antecedent of the pronoun "he."

"Students in on-line classes have to keep up with their assignments." The word "students" is the antecedent of the word "their."

The antecedent is the noun or pronoun replaced by a pronoun.

Examples:

When George got to 19th Street, hegot off the train. ("George" is the antecedent of the pronoun "he.")

You and I can finish this if we work together. (the pronouns 'you and I' are the compound antecedent of the pronoun 'we')