Demonstrative pronouns substitute for things being pointed out. They include this, that, these, and those. This and that are singular; these and those are plural.

The difference between this and that and between these and those is a little more subtle. This and these refer to something that is “close” to the speaker, whether this closeness is physical, emotional, or temporal. That and those are the opposite: they refer to something that is “far.”

• Do I actually have to read all of this?
  • The speaker is indicating a text that is close to her, by using “this.”
• That is not coming anywhere near me.
  • The speaker is distancing himself from the object in question, which he doesn’t want to get any closer. The far pronoun helps indicate that.
• You’re telling me you sewed all of these?
  • The speaker and her audience are likely looking directly at the clothes in question, so the close pronoun is appropriate.
• Those are all gross.
  • The speaker wants to remain away from the gross items in question, by using the far “those.”

The antecedents of demonstrative pronouns (and sometimes the pronoun it) can be more complex than those of personal pronouns:

• Animal Planet’s puppy cam has been taken down for maintenance. I never wanted this to happen.
• I love Animal Planet’s panda cam. I watched a panda eat bamboo for half an hour. It was amazing.

In the first example, the antecedent for this is the concept of the puppy cam being taken down. In the second example, the antecedent for it in this sentence is the experience of watching the panda. That antecedent isn’t explicitly stated in the sentence, but comes through in the intention and meaning of the speaker.