A colon is a piece of punctuation that looks like two dots stacked on top of each other (:).
A colon can be used to alert the reader to the fact that a list is coming. The words before the colon must be a complete thought. Look at the example:
Mom needs three things at the store: milk, bread, and lunchmeat.
Notice that the first part of the sentence is a complete thought: Mom needs three things at the store.
When we put a colon after that complete thought, we can add the list items to finish the sentence.
Here are more examples:
Billy has three favorite colors: red, green, and orange.
Jan visited four countries this summer: Austria, Germany, France, and Italy.
Here is a sentence with a list that does not need a colon because the words before the list are not a complete thought: Jim plays basketball, baseball, and soccer.
If we wanted to include a colon before the list, we would need to change the sentence to have a complete thought before the list, like this: Jim plays three sports: basketball, baseball, and soccer.
Place a colon before a list if the first part of the sentence is a complete thought.
▶It’s your turn. Which of these sentences needs a colon before the list? Bob has a dog, a cat, and three goldfish. or We have three trees in our yard an oak, an elm, and a hackberry. Did you put a colon into the second sentence, before the list of trees? Good for you!