Regular Expressions 101

^start of line

Non-Capturing Group(?:www\.|)

1st Alternativewww\.

wwwthe literal text www (case sensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

2nd Alternative — matches an empty string

Group 1(([^\.]+)\.[^\.]+)

Group 2([^\.]+)

Negated Character Class[^\.]+

+matches at least one character outside the set below:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Negated Character Class[^\.]+

+matches at least one character outside the set below:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^(?:www\.|)(([^\.]+)\.[^\.]+)

inner.ge.site.com
www.inner.ge.site.com
aaa.vk.site.ru
www.aaa.moscow.site.de
moscow.ru.site.ru