Commas and Introductory Interjections

Here's just a quick and easy lesson on commas and introductory interjection. An introductory interjection is a short (sometimes one word) statement or reaction. For instance, in this sentence Yes, I won the lottery! the word "Yes" is the interjection and the comma immediately follows. Another example would be, Whoa, I didn't see you behind me! I'm sure you can figure out what the introductory interjection is in this sentence.