To Set Off Appositives

Use commas to set off appositives. An appositive is a word or phrase that renames the noun or pronoun that comes before it.

My father, a great cook, makes the best egg rolls in town. (an appositive phrase)

To Set Off Introductory Phrases and Clauses

Use a comma to separate a long phrase or clause that comes before the main part of the sentence.

After checking my knee pads, I skated off. (phrase)

If you practice often, skating is easy. (clause)

To Join Two Independent Clauses

Use a semicolon to join two independent clauses when there is no coordinating conjunction between them.

My aunt has a new motorboat; I wish I were old enough to drive it.