In this lesson, we continue learning about regular expression syntax. In previous lessons, we learned that we can use square brackets to specify characters apart of a pattern we are looking for. Today, we take that concept a bit farther and target groups of letters such as the group of letters between the letter "a" and "e". Instead of specifying each letter between "a" and "e", we can use a hyphen to denote that we which to match all characters between "a" and "e". This allows us to write a lot less when creating patterns to search for. When working with regexes, it is important to learn how to use a hyphen to match patterns without having to write individual characters. That is the mean focus of this lesson, and if you understand how that works, feel confident in moving on to the next lesson.