In today's Regular Expression lesson, for Tuesday, Feb 9, 2021, we are looking at a common problem faced by many developers who are using a regex that allows us to restrict possible usernames. When creating an application that allows users to sign up using usernames, it is important to catch any restricted usernames efficiently and effectively using a regular expression. In this lesson, we see how to do this, by creating a regular expression that catches certain restraints. We are able to do this using a combination of tools we learned in previous lessons. Learning regex character classes allows you to be a better developer and coder. Learning to code in 2021 is essential and if you are a beginner make sure to check out our course tutorials here at We Will Code! Make sure to watch all our coding tutorials for free and feel free to comment and ask questions anytime!