This is used with singular or uncountable nouns (i.e. this egg or this music). These refers to plural nouns (i.e. these cookies). When the noun is omitted after this and these, they become pronouns (i.e. turn this off when you leave). Demonstratives are words we use to indicate nouns in a sentence.

When to use it and this?

The main difference between it and this is that it is a third person singular personal pronoun whereas this is a demonstrative adjective and pronoun. The functions and meaning of these two words also change due to the differences in their grammatical categories.

How do you use this in a sentence?