How are nonrestrictive phrases typically punctuated in a sentence?

Nonrestrictive phrases are additional pieces of information that can be removed from a sentence without changing its fundamental meaning. They provide extra detail but are not essential to the overall message. Because these phrases add context without narrowing the meaning of the subject, punctuation is necessary to set them off from the rest of the sentence.

Commas are used before and after nonrestrictive phrases to clearly indicate that the information can be omitted. For instance, in the sentence "My brother, who lives in New York, is visiting this weekend," the phrase "who lives in New York" is nonrestrictive; it adds information about "my brother," but the main assertion remains clear without it.

The other punctuation marks, such as semicolons, colons, or the lack of punctuation, do not serve the purpose of clearly delineating a nonrestrictive phrase. Semicolons are typically used to link independent clauses, colons introduce lists or explanations, and no punctuation would merge the phrase with the main sentence, potentially causing confusion. Thus, commas are the correct form of punctuation to use with nonrestrictive phrases.