Privet. We use this/these to refer to people and things, situations and experiences that are close to the speaker or very close in time . Examples: Who is this new boy? Who are all these poor people? We use that/those to refer to people and things, situations and experiences that are more distant, either in time or physically. Examples: Do you remember that boy from America who came here last year? Did you return those books to the library yesterday?

This is pointing to something that is very close. For instance, if there is a pencil right in front of me, I would refer to it as "This". That is pointing to something a bit more far away!.