• Semicolons replace commas in a list whose items themselves contain commas. For example:
Liz tried several things to treat her allergies: taking over-the-counter medications such as Chlor Trimeton, Zyrtec, and Claritin; alternating those drugs; wearing mosquito netting over her head; and, finally, swearing never to go outside in the spring.
• Use a semicolon—not a comma—to separate independent clauses that don’t have coordinating conjunctions (and, but, or). For example:
Yes, I see the mess you’ve made; you’ll be cleaning it up tomorrow.
• Use a semicolon between main clauses joined by a conjunctive verb (however, therefore, then). For example:
“However” is not a coordinating conjunction; therefore, it cannot be used by itself to link two clauses.
• Do not use a semicolon to separate an independent clause from a clause dependent on it. Use a comma instead. For example:
Their inane, vacuous chatter made it difficult to concentrate, especially because she was trying to write.
(An incorrect example would be: Their inane, vacuous chatter made it difficult to concentrate; especially because she was trying to write.)