Non-Capturing Group(?:https?://)? ?repeats the group contents below at most once:
httpthe literal text http (case sensitive) s?optionally matches the literal s (11510 / 1638 / 7316) (case sensitive)
Non-Capturing Group(?:www\.)? ?repeats the group contents below at most once:
wwwthe literal text www (case sensitive) \.the literal . (4610 / 568 / 2E16)
\S+any character that is not Unicode whitespace, repeated at least once
\.the literal . (4610 / 568 / 2E16)
\S+any character that is not Unicode whitespace, repeated at least once