Read the following sentences:

• Teacher tells Isabel to go to the library.

• Uma prefers watching movies to attending parties.

If there is more than one Isabel or Uma then it would be difficult to tell which one is being referred to.

It would be clearer if there is any additional information specifying which Isabel or Uma is being referred to.

Compare the above sentences with the ones below:

• Teacher tells Isabel, my best friend, to go to the library.

• Uma, your housemate, prefers watching movies to attending parties.

The phrases my best friend and your housemate give us additional information about Isabel and Uma. These are called appositives.

An appositive is a noun or noun phrase that immediately follows another noun or pronoun to give additional information or explanation about it.

An important point to remember is that an appositive is separated from the rest of the sentence with commas.

This is done when the appositive can be removed without changing the meaning of the sentence.