Regular expressions are formulas that can be used to match strings of text that follow some pattern. They allow their users to succinctly express a set of character matching rules that would otherwise require a large number of switches and logical operations.
When you first see a regular expression, it may appear somewhat intimidating and complex. But, in reality, regular expressions can be as simple or involved as you wish and still be effective. Once you understand the meaning of a handful of special regular expression characters (called metacharacters), you'll be able to match filename patterns with ease.
This help file will not provide an in-depth tutorial on the formation of regular expressions, simply because a large number of these exist on the Internet today for free. Simply visit your favorite search engine and enter "regular expressions" into the search box. You'll find a variety of guides and other useful materials to help you along.
FolderSizes supports the ECMA-262 grammar with only minor modifications. Learn more about this standard here: