Regex Cheat Sheet for Beginners

Regular expressions look cryptic until you learn the handful of building blocks. Here's a beginner's cheat sheet.

Character classes

Pattern	Matches
.	any character (except newline)
\d	a digit (0–9)
\w	word character (a–z, A–Z, 0–9, _)
\s	whitespace
[abc]	a, b, or c
[^abc]	anything except a, b, c
[a-z]	any lowercase letter

Quantifiers

Pattern	Meaning
*	0 or more
+	1 or more
?	0 or 1 (optional)
{3}	exactly 3
{2,5}	between 2 and 5

Anchors

Pattern	Meaning
^	start of string/line
$	end of string/line
\b	word boundary

Groups and alternation

• (abc) — a capturing group
• (?:abc) — a non-capturing group
• a|b — match a or b

Common flags

• g — global (find all matches)
• i — case-insensitive
• m — multiline (^/$ match each line)

A worked example

Match a simple time like 09:30:

^\d{2}:\d{2}$

Two digits, a colon, two digits, anchored to the whole string.

Practice

Test patterns live against your own text with the regex tester, and see common regex patterns for ready-made examples.