A colon (:) can be used to emphasize a word or phrase. Be sure to write a complete thought before the colon. Look at this example.
My little brother eats only one thing: hot dogs.
As far as I can tell, college is good for only one thing: meeting girls.
I have been waiting my entire life for this: graduation.
Use a colon to emphasize a word or group of words that finish off a complete thought.
Now you try it. Insert a colon into this sentence. Before you take off with the car, I have only one word for you gas. Did you figure out that you need to put a colon before the word gas? Good for you!