If is likely that your Google Analytics tracking code resides, along with everything else that constitutes your website, on a development or testing/staging server before you deploy it to your production server.
To include or exclude Google Analytics data that is generated on any server, you can apply a profile filter that specifies the exact version of your domain, such as:
For profiles that should contain production data only, a best practice is to apply an include filter for your production domain only:
As a general note, once you define an include filter for hostname (or any other dimension), all other versions of the hostname will be excluded, so there’s no need to apply a hostname include and an exclude filter to the same profile.
Also note above that the \ serves as the regular expression “escape” character so the dot is interpreted as a literal dot and not as a wildcard match single character.