The anchor text itself can be anything you want, from keyword phrases to generic calls to action, to domain names, or whatever else. The actual URL that the link itself points to though, should ideally have the full HTTP or HTTPS part to avoid any possible issues, as Techxan noted.
I would post some examples, but my account is new here (been lurking for years though, lol), and I don't think I can make any posts with URLs in them at this time.