Semicolon;

Don’t confuse it with the colon (see #3). Think of a semicolon as a supercomma, strong enough to hold independent clauses apart.

Use a semicolon

• in lists that already contain commas,

The study included data from four cities: Houston, Texas; San Diego, California; Cleveland, Ohio; and Baltimore, Maryland.

• between independent clauses not joined by a coordinating conjunction in a compound sentence,

The hours were terribly long; no one got much sleep.

• between independent clauses in a compound sentence when the clauses are joined by a conjunctive adverb or a transitional phrase instead of by a coordinating conjunction.

No one got much sleep; however, it was a very valuable experience.

The company was owned by the employees; therefore, everyone was motivated to work hard.