Can I put any URL in a link?

You bet. If you can get to a URL using your browser, you can put that URL in a link. Note, however, that some browsers support URLs that others don’t. For example, Lynx is really good with mailto URLs (URLs that enable you to send electronic mail to a person’s email address). When you select a mailto URL in Lynx, it prompts you for a subject and the body of the message. When you’re done, it sends the mail.