Regex Explained for Developers

What are regular expressions?

Regular expressions (regex) are patterns that match text. They are used for validation, search-and-replace, and parsing in almost every language and editor.

Common regex concepts

• Anchors: ^ and $ match the start and end of a string
• Character classes: \d for digits, \w for word characters
• Quantifiers: +, *, ? for one-or-more, zero-or-more, optional
• Flags: g (global), i (case-insensitive), m (multiline)

Test your patterns live with our Regex Tester. For learning and explaining regex, use the Regex Explainer.