Explain why the phrase in this sentence is nonrestrictive, or nonessential to the sentence: My youngest brother, Julian, is already taller than I am.

The name "Julian" is not necessary in the sentence. The writer can have only one youngest brother, so the name "Julian" is extra information. Thats the response edgen gave me.

The phrase Julian is nonrestrictive, or rather, nonessential, because of the meaning of the sentence. The sentence says youngest brother - this means that there can only be one youngest brother, so it is unnecessary to actually name him. By stating that the brother is the youngest one, we already know who the speaker is referring to.