Impersonal pronouns can replace personal pronouns. They are more abstract and generally mean “a person.” There are just two impersonal pronouns:
Try to use one sparingly in formal writing, as it can sound a bit stiff. Similarly, it is a rather vague pronoun, and often you can be more specific:
Vague: In The Divine Comedy, Dante often tries to outdo his teacher Virgil. One might argue that it reveals an “anxiety of influence.”
Better: In The Divine Comedy, Dante often tries to outdo his teacher Virgil. Harold Bloom argues that such poetic competition reveals an “anxiety of influence.”
Finally, note that one can also be classified as an indefinite pronoun and that it is included in the personal pronouns.
Demonstrative pronouns are used for pointing at something, as you might in a demonstration:
Allow me to demonstrate how to drive this Porsche.
There are just four demonstrative pronouns:
And this is what those pronouns look like in a sentence:
These cupcakes are wonderful.
This essay is plagiarized.
Those onions make me cry
That is a great idea.
In the first three examples, the pronoun acts like an adjective (it modifies a noun). In the last it acts like a noun.
Notice that this and these refer to things close by, whereas that and those are reserved for more distant objects.