There is often some confusion about what is a demonstrative pronoun and a demonstrative adjective. This arises from the fact that the same words are used for both - the most popular being this, that, these and those.
Basically, the only difference between demonstrative pronouns and demonstrative adjectives is that demonstrative adjectives modify nouns, and are followed by the nouns, while demonstrative pronouns replace the noun.
So demonstrative pronouns are the same pronouns that are also used for demonstrative adjectives - this, that, these and those. How do you tell the difference? The difference is in the sentence structure.
For example, here are some demonstrative pronouns that are taking the place of the underlined noun phrase:
There are three other words that are sometimes used as demonstrative pronouns - such, none, and neither.
Typically, when you use a demonstrative pronoun, you will either need to indicate what you're talking about by pointing or otherwise gesturing toward it, or your listener(s) will need to be looking at it as well. For this reason, demonstrative pronouns are mostly used in spoken English.
However, demonstrative pronouns can be used in written English if the context makes clear the noun to which the demonstrative pronoun refers. A list, for example, in close proximity to (either before or after) "these" or "those" would be clear enough.
Or you could refer to a description of an object, activity or situation as "this" or "that" if you do so immediately following the description.
As mentioned earlier, the four demonstrative adjectives are also this, that, these and those. They are adjectives because they modify nouns. That means they come before nouns in a sentence. For example:
Demonstrative adjectives indicate exactly which noun the speaker means and where it is (or they are) relative to the position of the speaker.
Then he always follows the demonstrative with any other accompanying adjectives in their proper order and finally, the noun.
So what is a demonstrative pronoun? It's a single demonstrative word that takes the place of a noun, a noun phrase, a string of noun phrases, an activity, or a situation in both written and spoken English.