The four common demonstrative pronouns are this, that, these, those. We use them to indicate the person, thing or place referred to, with this used to refer to someone or something nearer (that is, nearer to the person speaking) while that refers to the farther one. If there is more than one person, thing or place referred to, we use these, which is the plural of this. Those is the plural of that.

A demonstrative pronoun is no longer a demonstrative pronoun if it comes before a noun that it modifies; it becomes a determiner. If it stands on its own without modifying or describing any person, place or thing, it is a demonstrative pronoun.

Examples:

Pronoun: This is the same story I heard from him before.
Determiner: This story is the same story I heard from him before.

Pronoun: That is not a bird; it is a kite.
Determiner: That bird looks like a kite.