Demonstratives

This vs. that
The singular demonstrative pronouns are this and that.

This is used to point out something near to the speaker in space or time:

I brought this from home.
That indicates something more distant:

My memory stick? I forgot that at home.
These and those
The demonstrative pronouns have plural forms, used to replace a plural noun. The plural of this is these:

I’ll take these. They’re perfect!
The plural of that is those:

Those are chameleons.