You can, of course, also link to external content on the internet.
Input
http://example.net/ [[http://moinmoin.in/|MoinMoin Wiki]] ftp://example.org/pub/ {{http://static.moinmo.in/logos/moinmoin.png}}
Display
As you can see, [[...]] sets a link to the target, {{...}} embeds the target, which is especially useful for pictures.