Regex Guides — Basics · Flags · Quantifiers · Groups | AG Regex | AG Regex

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From basic concepts to flags, quantifiers, and groups, we've briefly summarized the essentials you need to learn regular expressions.

What Is a Regular Expression

Grasp the concept of regular expressions and where they are used in five minutes.

Flags in Full: g i m s u y

Understand the six flags that change how a regex behaves, with examples.

Quantifiers and Greedy vs. Lazy Matching

Understand the difference between *, +, {n,m} and adding a ?.

Groups and Lookahead/Lookbehind

A rundown of capture groups, named groups, and lookaround.