To aide in writing examples, there are some reserved names/addresses that people can use. For instance

example.com example.net example.org .example .test .invalid

are all reserved for writing examples, so if you accidently Cut and paste an example in you won't start irritating anyone, or if the domain you're giving as an example suddenly is registered you won't confuse people. (RFC:2606)

The people at 'somewhere.com' get a lot of spam. Please, don't make it worse for them.

For networking the range 192.0.2.0/24 is reserved for documentation and example code (RFC:3330)