Semicolon
Rule 5. Use the semicolon to separate units of a series when one or more of the units contain commas.
Example This conference has people that have come from Boise, Idaho; Los Angeles, California; and Nashville, Tennessee.
Rule 4. If these introductory words are followed by fewer than three items, do not use a semicolon. Simply enclose the introductory words in commas.
Example You may be required to bring many items, for instance, sleeping bags.
Use a semicolon to join two independent clauses. (This eliminates the need for a comma and a conjunction.)
Example: Casey read a book; then he did a book report.
Use a semicolon to separate items in a series when those items contain punctuation such as a comma.
Example: We went on field trips to Topeka, Kansas; Freedom, Oklahoma; and Amarillo, Texas.
Rule 1. You may use a semicolon in place of a period to separate two sentences where the conjunction has been left out.
Examples Call me tomorrow; I will give you my answer then.
Rule 2. Do not use a semicolon in front of words such as therefore and however if they do not connect two complete sentences or are used as interrupters.
Examples I would, therefore, like a response. I would be happy, however, to volunteer for the Red Cross.
Rule 6. Use the semicolon between two sentences that are joined by a conjunction but already have one or more commas within the first sentence.
Examples When I finish here, I will be glad to help you; and that is a promise I will keep.
Rule 3. Use a comma or a semicolon before introductory words such as namely, that is, i.e., for example, e.g., or for instance when they are followed by a list of three or more items and preceded by a complete sentence.
Examples You may be required to bring many items; e.g., sleeping bags, pans, and warm clothing. OR You may be required to bring many items, e.g., sleeping bags, pans, and warm clothing. NOTE: i.e. means that is e.g. means for example