---
note type:
  - theory
date: 2026-06-04
done:
link: https://www.rexegg.com/regex-quickstart.php
---
Regular expressions (regex) are patterns used to match character combinations in strings, offering a powerful way to search and manipulate text that can replace dozens of lines of code. While the syntax can seem complex, understanding core components like **character classes** (e.g., `[0-9]` for digits, `\w` for word characters), **quantifiers** (e.g., `+` for one or more, `*` for zero or more), and **anchors** (e.g., `^` for start, `$` for end) allows for effective pattern matching.

Check out the link, which is really useful in showcasing the rules.

Use: https://regex101.com/ to build and validate.