Living in a world of tiny Crackberry keyboards, instant messaging and emoticons causes some of us to occasionally throw the rules of capitalization out the window when we're online. It's true that this is much less likely to cause a problem now compared to a few years ago. But you should still take care in using uppercase versus lowercase because it can matter in e-mail and Web addresses in some instances.
Fortunately, by remembering a few simple rules you should be able to avoid problems. First, let's deal with Web site addresses, or URLs as they are technically known.
What to Know about Case Sensitivity in URLs
A URL (for Universal Resource Locator) is simply a friendly version of an Internet address that takes you to a particular page on a Web site. This can be a home page or any page deeper within a site.
You never have to worry about capitalization if you are using only a top-level domain name—that is, a URL ending in .com, .net, .org, .biz and the like, including country-specific domains such as .ca or .us and so on. Using my firm's site address as an example, www.practicepro.ca is the same as www.practicePRO.ca, WWW.PRACTICEPRO.CA or even WwW.pRaCtIcEpRo.Ca.
In some instances, however, when a URL includes a specific directory or file name, case does matter. If the characters following the right-most slash ("/") in your URL include a .htm, .html, .pdf, .asp or other three- or four-letter extension, you are entering a URL for a specific file. Depending on the type of operating system and Web server setup in use, the directory and file name portions of a URL can be case sensitive. Windows servers do not differentiate between uppercase and lowercase, but Unix/Linux servers do.
Bearing in mind that Web site design conventions dictate that consistency should be followed, the best practice is generally to make all letters of a URL lowercase. But, of course, not everyone follows the best practices.
Why do people include mixed capitals and lowercase letters? They actually have good intentions and are following a common practice in the computer world of using capitals to make multiple words strung together more readable. This is called Pascal Notation.
For example, www.ThisSampleWebAddressIsVeryLong.com is much easier to read than www.thissamplewebaddressisvery long.com.
Another option is using underscores to make things more readable, such as in www.sample_web_url.com. But as many have learned, underscores can be confusing when the URL appears in underlined form in a document, since they look like blanks or spaces in the URL:
Accordingly, here's what you do if you get the dreaded "HTTP 404 - File not found" error message when you're trying to connect to a URL that includes a specific file name: Check not only that you typed the URL correctly, but also particularly check for underscores and correct capitalization if your URL includes some uppercase letters. There is a chance that a missing underscore or wrong case is the reason you aren't connecting to that page.
And here's a further trick for when you're having trouble connecting to a very long URL that you manually typed (or that someone else programmed as a link on a Web page, for that matter). One by one, starting at the right end of the URL, delete each part of the URL
after the successive /'s and see if your browser can find the site. Hit Enter after deleting each successive part of the URL to search for that page. You will often be able to connect to the site on a page that is one or more levels above your page. You can then dig deeper for the specific page to which you were trying to connect.
As an aside, if you're including a URL on your business card or in an article or similar type of document, remember that you don't have to include the http:// portion of the URL. I don't know about you, but this is really good news for me because I can never remember if it is // or \\.
Pointers for E-mail
When dealing with e-mail addresses, remember that any part after the @ sign will never be case sensitive. However, although it will be very rare, case may matter for the part of the e-mail address before the @ sign.
Another instance where case matters in e-mail relates to a too commonly overlooked rule of Netiquette (that is, etiquette on the 'Net): I'm talking about the use of capital letters in the text of an e-mail message. Please note: You should only rarely type e-mail messages in uppercase letters. Typing something in uppercase is considered the textual equivalent of shouting. On the Internet you should shout only if you really want to emphasize something—and you should do this sparingly—or if you are very mad—and you should do that even more sparingly (or not at all).
If you really feel the need to type everything in capitals, just do it—get it out of your system. But don't send the message afterward. Instead, save it to your drafts folder and take a second look at it when you've cooled down a bit. If you haven't cooled down after a reasonable time, consider a phone call or the sneaker-net instead of an e-mail because any issue that hot should be dealt with in a more direct fashion.
Thus, with a few exceptions, you can avoid problems with URLs and e-mail addresses if you stick to lowercase. Again, these exceptions may arise when you are dealing with the folder or file name portion of a URL or, on very rare occasions, the name portion of an e-mail address.
So in sum, frequently capitals letters don't matter at all, but it is safer just to stay away from that shifty Shift key.