\s+any whitespace character, repeated at least once
Onthe literal text On (case insensitive) .+any character (except for line terminators), repeated at least once
atthe literal text at (case insensitive) .+any character (except for line terminators), repeated at least once
wrote:the literal text wrote: (case insensitive) +matches at least one character from the set below:
\wany word character
\Wany non-word character
i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters