ELI5: Explain Like I'm 5

regex

Regex stands for "Regular Expressions", and it's a way to identify specific patterns in text. It's like finding specific words in a book. Regular Expressions can tell a computer which words or characters to look for, and then tell it what to do once it finds them. For example, a Regex can search a website for all the email addresses, or all the words that start with a certain letter, or all the words that are three letters long. You can use Regex to find anything, as long as you know the pattern of the thing you're looking for.