Regular Expressions (RegEx)
RegEx Tutorial (opens in a new tab)
Renowned has being not very human readable, regular expressions are used for glob and pattern matching.
Check out https://www.regular-expressions.info/tutorial.html (opens in a new tab) to learn more.
A common application of them is when using the unix command-line utility
grep (https://en.wikipedia.org/wiki/Grep (opens in a new tab)) to search across files on a computer.