\w+any word character, repeated at least once
@the literal @ (6410 / 1008 / 4016)
\w{1,63}any word character, repeated between 1 and 63 times
\.the literal . (4610 / 568 / 2E16)
{3}matches exactly 3 characters from the set below:
a-zone character from a (9710) to z (12210) (case sensitive)
g modifier: global. Finds all matches instead of stopping after the first