It provides additional information about the noun it follows
an appositive is a noun or a pronoun that appears next to another noun or pronoun and identifies renames,or explains it
For example:
My friend John, a talented musician, played the guitar at the party.
In this sentence, "John" is the appositive, providing additional information about "my friend."
For example:
The novel, a classic work of literature, has been translated into many languages.
Here, "aclassicworkofliterature" is an appositive phrase, further describing "the novel."
when an appositive or an appositive phrase is nonessential, or can be removed without altering the basic meaning of a sentence, it is set off with a comma.
when an appositive or an appositive phrase is essential to the meaning of a sentence, commas are not used
an appositive or an appositive phrase is a great way to combine two short, choppy sentences into one more-effective sentence. In the example below, two sentences are combined into one sentence by using appositive phrase.
before: eyad's car is an old station wagon. eyad's car cannot handle icy roads
after : eyad's car, an old station wagon, cannot handle icy roads