A demonstrative pronoun is one of four words used in the place of common nouns in a sentence. The singular words "this" and "that" and their plurals "these" and "those" are the demonstrative pronouns in English. These words are used to indicate a known object that is either near or far from the speaker or that exists in the present or past.
Pronouns are general words which stand in for certain nouns in a sentence. They often are used to refer to people, such as "she" and "who," or a thing, "it." Demonstrative pronouns are a small set of pronouns which also refer to things, but do so more specifically than the pronoun "it." Where "it" simply indicates some object or sexless animal, demonstrative pronouns will indicate whether that object is nearby or farther away.
The words "this" and "that" are the singular demonstrative pronouns. Using "this" indicates the object is present in the general area of the speaker. The word "that" indicates a specific object that is farther away, either out of arms reach or even out of sight. It may also indicate something that existed in the past. The word "these" is plural for "this" and "those" is plural for "that."
Just like nouns and other pronouns, a demonstrative pronoun can act as a subject or object in a sentence. Unlike personal pronouns, which change their spelling depending on their function in a sentence, whether a demonstrative pronoun is a subject or object is only determined by its place in the sentence. For example, in the sentence, "That is my favorite song," the word "that" is functioning as a subject, but in "I have never liked that," the word "that" is the object of the sentence.
A demonstrative adjective should not be confused with a demonstrative pronoun. Like most adjectives, demonstrative adjectives modify nouns but do not replace the nouns. For example, in the sentence "this tastes spicy," the word "this" is acting as a demonstrative pronoun because the speaker is referring to some unstated food object that he or she is eating at that time. In the sentence "this soup tastes spicy," on the other hand, "this" is acting like a demonstrative adjective because it is modifying the stated noun "soup."
Additionally, the word "that" may also function as a relative pronoun. Relative pronouns serve to link phrases together. For example, in the sentence, "She wanted to learn every recipe that was in her cookbook," the word "that" is functioning as a relative pronoun not a demonstrative pronoun.