Appositives are nouns that rename other nouns. We use them to give more information about someone or something that we've already named.
Mike and Bri graduated from UWEC, my alma mater.
My mom, a talented woman, produced a lullaby CD.
The author Victor Hugo was born in France.
My sister, a French teacher, studied in France.
They rename another word. What does that mean?
Esther is the subject of the sentence. It is also a noun. The word sister is renaming Esther. It is a noun that gives us more information about Esther. Both words are referring to the same person.
So, sister is a noun that renames another noun, Esther.
Do you know much about phrases? Phrases are groups of words, without both a subject and a verb, that come together to act as one part of speech.
The appositive is the single word that is doing the renaming (sister).
The phrase is that single word plus all of the words that are modifying it (my sister with dark hair).
There are two types of appositives, and it's important to know the difference because they are usually punctuated differently.
Nonessential - Use Commas
Most are nonessential. (These are also called nonrestrictive.) That means that they are not an essential part of the sentence, and sentences would be clear without them. Set these apart from the sentence with commas.
Note that some publications don't add commas to these if they are simply a name.
People who always add commas to nonrestrictive appositives would insist on using commas in that example since I only have one husband! However, some publications ignore using commas in this situation.
Essential - Don't Use Commas
Some are essential to the meaning of the sentence. (These are also called restrictive.) If these weren't in the sentence, the meaning of the sentence would be unclear.
Do you see how we need those in order to understand the meaning of those sentences?
Intensive pronouns are used to emphasize another noun or pronoun. We can also call these emphatic appositives. Never use commas with these.
To diagram these, put them in parentheses after the noun that they are renaming.
Add any words that modify it on slanted lines just like other modifiers.
You can use these to combine sentences. See this helpful PDF to try it out!
Other Helpful Resources