Congrats on finishing the lessons! We hope that they've given you a bit more experience with regular expressions and how to apply them in everyday use.
There are still topics within regular expressions that we have not yet explored, – things like greedy vs. non-greedy expressions, posix notation and more. We will try to elaborate more on these in future lessons.
If you found the lessons useful, please consider donating ($4) to support RegexOne. Your contribution will help keep the servers running and allow us to add even more material in the future. If you have questions or suggestions on how to improve the site, feel free to get in touch via Twitter (@regexone) or email (firstname.lastname@example.org)!
For now, continue onto the practice problems to learn how to put regular expressions to practical use.