A semicolon is a punctuation mark (;) indicating a pause, typically between two main clauses, that is more pronounced than that indicated by a comma. The semicolon is considered more of a formal mark of punctuation than the comma. The semicolon is actually a combination of two punctuation marks: the comma and the period. Thereby, it reflects more than a typical pause; it is a stronger break, but not a complete stop. There are three key uses for the semicolon:
The quarterback threw the ball deep for a much needed touchdown; it just flew over the receivers head ending the game.
If those two independent clauses had been connected with the cooridinating conjunction but, a comma would have worked instead.
The quarterback threw the ball deep for a much needed touchdown, but it just flew over the receivers head ending the game.
Keep in mind that the words however, moreover, nevertheless, and therefore are not cooridinating conjunctions. Instead, they are conjunctive adverbs. When one of these words separates two independent clauses, a semicolon is needed.
This is just a simple idea; nevertheless, I’d like you to give it some thought.
If you’ll notice, without the conjunctive adverb, alone with the comma, you’d be left with a comma splice, which is incorrect grammar.
This is just a simple idea, I’d like you to give it some thought. (Comma splice)
Additionally, semicolons are required when more than two independent clauses are connected in a series . . . even when the final portion of the series is conjoined by a coordinating conjunction.
The probable conflicts are worrisome; most likely the team will lose focus; and the coaches will feel bad about the loss, but the team must move forward.
If you punctuate a clause from within with commas, one cannot use another comma to separate that clause from another. In this instance, a semicolon is required to make a more formal pause.
The audience, whose attendance reached 100,000, filled the stadium to capacity; and the stairways were sold as standing room only.
3. Utilize a semicolon to divide parts of a series that also contain commas.
Selected in the draft were James Smith, 19, of Rochester; Steve Jones, 20, of Lansing; and Billy Toms, 18, of Battle Creek.
In essence, the main use of the semicolon in the example above is for organization. It smooths out the elements in a series so that they remain important.
Overall, a semicolon is useful when it designates limits in a series where commas are also used. At its best, the semicolon is used for clarification.