Commas. In a list consisting of three or more words or phrases, use commas after each item except for the last.
Example: Each boy wore khakis, a white dress shirt, and dress shoes.
When directly addressing by one’s name or title, use commas to set off the direct address.
Example: Each of the boys, Mr. Davis, presented himself with dignity and authority.
When joining two independent clauses witha coordinating conjunction (FAN BOYS: for, and, nor, but, or, yet, so), place a comma immediately before the conjunction.
Example: The swim team ate at a fast food restaurant before their swim meet, and some of the swimmers became ill after competing.
Place a comma following introductory elements in a sentence.
Example: In 1998, Clinton invited the SDSU Marching Jackrabbits to march in his inaugural parade.
Example: After his capture, Saddam Hussein stood trial for his actions.
Semicolons. Use semicolons between two independent clauses or between two clauses of varying topics to avoid run-on sentences.
Example: William Shakespeare is known for more than his plays and poetry; he is famous for inventing the word assassination.
Semicolons are often used with words such as however, accordingly, therefore, besides, indeed, thus, and then.
Wrong: I always wanted to teach math, however, I became a podiatrist instead.
Right: I always wanted to teach math; however, I became a podiatrist instead.
The exception to the semicolon rule is when combining short independent clauses.
Example: You win some, you lose some.