THIS - THAT - THESE - THOSE

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.)