Colons and Semicolons in Lists

A complex list is a list where at least one of the items already has a comma inside it. When that happens, commas alone get confusing, because you cannot tell where one item ends and the next one begins. The fix is to use a semicolon between the items instead. Look at this example: On our vacation, we plan to visit Athens, Greece; Cairo, Egypt; and Rome, Italy. Each stop is a city and a country, so each one has its own comma. The semicolons act like extra-strong separators that keep the three stops apart. Even if only one item in the list has a comma, you still use semicolons between all the items. That keeps the whole list matching and easy to read.

A colon is the punctuation mark that looks like two dots, one above the other. You can use a colon to introduce a list, but there is one important rule: the words before the colon must be a complete sentence that could stand on its own. Before the class performance, the teacher reminded the students of three important tips: speak loudly and clearly, smile, and do not forget to bow. The part before the colon is a full sentence, so the colon works. Think of the colon as a little drumroll that says, get ready, here comes the list. Do not put a colon right after words like is or including, because then the part before it is not a complete sentence.

A complex list is a list in which one or more of the items already contain punctuation, usually a comma. In a complex list, use semicolons between the items. This clearly separates each item and makes the list easier to read. We tried pizza in Naples, Italy; Naples, Florida; and Naples, New York. Each item is a city and a state or country, so each one already has a comma. The semicolons keep the three places from blending together. The most common mistake is separating the items with commas anyway, like this: We tried pizza in Naples, Italy, Naples, Florida, and Naples, New York. Now it looks like a list of six places instead of three. When the items have their own commas, semicolons do the separating.

Colons can be placed after an independent clause to introduce a list. An independent clause is a group of words that forms a complete sentence all by itself. Before the field trip, the teacher reminded the class of the three important rules: stay with your group, speak in a quiet voice, and do not touch the exhibits. The words before the colon make a complete sentence, so the colon is allowed to do its job of announcing what comes next. A helpful way to think about it is that the colon points forward and says, here is what I was talking about. If the words before the colon are not a complete sentence, do not use a colon there.

We use semicolons to punctuate a complex list. A complex list is a list where the items already contain commas. For example: I visited Paris, France; Paris, Texas; and Paris, Illinois. Each place name has a comma between the city and the state or country, so semicolons step in to separate the three places. Without the semicolons, the sentence would be one long string of commas and nobody could tell which city belongs with which state.