demonstrate  (verb): to show; to indicate; to point to

A demonstrative pronoun represents a thing or things:

  • near in distance or time (thisthese)
  • far in distance or time (thatthose)
 near •far ⇒
singular ?thisthat
plural ???thesethose

Here are some examples with demonstrative pronouns, followed by an illustration:

  • This  tastes good.
  • Have you seen this?
  • These  are bad times.
  • Do you like these?

  • That  is beautiful.
  • Look at that!
  • Those  were the days!
  • Can you see those?

  • This  is heavier than that.
  • These  are bigger than those.
Do not confuse demonstrative pronouns with demonstrative adjectives. They are identical, but a demonstrative pronoun stands alone, while a demonstrative adjective qualifies a noun.
  • That  smells. (demonstrative pronoun)
  • That book is good. (demonstrative adjective + noun)

Normally we use demonstrative pronouns for things only. But we can use them for people when the person is identified. Look at these examples:

  • This  is Josef speaking. Is that Mary?
  • That  sounds like John.

sources : Original Link