Such resources are commonly other pages, but of course they can be much more than simple pages: things like executable programs, zipped files, audio-visual files (such as Flash or MP3 files), e-mail addresses, or indeed anything that can be stored and then retrieved (with or without being secured via username/password or other means).

To be pedantic, such a character strings are properly called Uniform Resource Identifiers (URIs). Each URI may be a Uniform Resource Locator (URL) or a Uniform Resource Name (URN), or both, as explained here on Wikipedia.

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My personal view is that when you're creating content (web pages, e-mails, or whatever) it's a sort of criminal negligence -- a sin of omission, if you will -- to create regularly refer to web resources by plain text. For example, you'll notice that nearly every one of my resource references on iTWire pages are live links (with pop-up tool tips to boot), and I do the same when I'm creating e-mail messages.

You should make it dead easy for the readers of your web pages or e-mail messages to simply click on live links and not force them to access the resources by some indirect method (such as having to copy-and-paste the URL string).

In particular, I see so many e-mail messages referring to web sites URLs via plain text strings and with the author's signature at the bottom with an e-mail address composed of plain text instead of a live link of the form mailto:some_body@some_domain.com (probably because many people don't even realize there's a "mailto:" option they should always use).
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One of the banes of the web surfer's existence is the often complex or lengthy character strings that make up  URLs on far too many web sites.

It is all too common for URLs to be stored in web pages as plain text rather than as live hyperlinks. It can be a real nuisance to have to type them into a browser's address bar if you have to do it more than a very few times. It's bearable if you only have to do it occasionally, but even then only when the string is short, say, not more than twenty characters or so.

It's very bad practice, and a negative aspect of far too many web sites, to have URLs that are too cryptic, too long, or both. Far too many web designers and developers regularly build URL structures that are not user-friendly.

In some cases, this is not so much their fault but rather due to the middleware infrastructure (web server, database manager, etc) that they use to build their sites. You know what I mean: every now and then you come across a URL that seems to go on forever, way beyond the end of the address bar window, and one which is so complex that you'd never be able to manually key it in even if your life depended on it.

The issue boils down to this. If the URL is longer than 15 characters  or so, what's the best way to handle it in the web page that you're posting or the e-mail message that you're going to send off?

PLEASE READ ON...