This, that, these and those are demonstrative adjectives.

This is used to refer to a single person, thing or place that is close to the speaker.

That is used when the person, thing or place is more distant.

    • This computer is easy to use.
    • That coat on the chair is mine.
    • This person is my colleague.
    • That man over there is my boss.
    • This picture is clearer than that one.
    • This is my seat and that one is yours.

These is the plural form of this.

Those is the plural form of that.

    • These letters are urgent.  Please post them immediately.
    • Those men in the street are policemen.
    • I like these shoes.  They’re very comfortable.
    • Those shoes on the shelf are very expensive.
    • I like these shoes better than those shoes.
    • These books are more interesting than those (books).
  • In formal contexts we can use that and those for ‘one(s)’.
    • The most surprising announcement was that made by the Prime Minister.
      (That means the announcement, the one made by the Prime Minister)
    • A shuttle service is available for our guests.
      Those interested should enquire at the reception desk.
      (Those means the guests, the ones interested.)

Note: This, that, these and those can also be demonstrative pronouns when used to replace a noun.