diff --git a/regex b/regex
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+---
+tags: [ patterns ]
+---
+
+<char|pattern>? match 0..1 characters or patterns (`?` must be escaped in GNU sed BRE)
+<char|pattern>* match 0..more characters or patterns
+<char|pattern>+ match 1..more characters or patterns (`+` must be escaped in GNU sed BRE)
+
+<char|pattern>{<count>} match `count` characters or patterns (`{` and `}` must be escaped in GNU sed BRE)
+<char|pattern>{<from..to>} match `from`..`to` characters or patterns (`{` and `}` must be escaped in GNU sed BRE)
+
+[<characters>] match any mentioned character
+[^<characters>] match any not mentioned character
+
+# We don't distinguish between single char patterns below and complex patterns:
+
+^<pattern> match the beggining of a string
+<pattern>$ match the end of a string
+
+(<pattern1>|<pattern2>) match any of two patterns (`|` must be escaped in GNU sed BRE)