Demonstratives.

THIS is used for people or things that are close to us.
This book is expensive. (You are holding it)
THAT is used for people or things that are a distance from us or not present.
That trip was fun (last year)
THESE expresses something which is near you and plural.
These shoes are nice.
THOSE refers to things that are far from us and plural.
Those bottles are empty.

Just remember: This, these = near, That, those = far.

Online activities Here.