Among the excellent advice in Jakob Nielsen's latest essay, Top Ten Web-Design Mistakes of 2002 is the terse instruction URL > 75 Characters. Why? "Long URLs break the Web's social navigation because they make it virtually impossible to email a friend a recommendation to visit a web page," Nielsen explains.
This is good advice, but how can you follow it at the same time as creating the meaningful URLs recommended by web services developer Craig Johnson? He points out that, If URLs don't carry useful information, then it's less likely they'll be linked into emerging web-based applications and semantic grids, which could cut your site off from some powerful resources. He also links to an article by Peter Seebach, which argues persuasively that making URLs accessible is itself a contributor to usability.
Does this mean that it's going to be impossible to have URLs that combine usability with utility? How can you compress enough meaningful information into a URL and still keep it to less than 75 characters? There's no doubt it's going to be difficult, but with a little bit of thought and creativity it should be possible to meet both objectives at the same time. Here are a few ideas:
Where possible, use a short root domain. Jakob Nielsen saves quite a few characters, simply by virtue of having a short domain name (useit.com), and he saves four more by omitting the "www.". Unfortunately, we don't all have that option here, I'm stuck with "howto.looselycoupled.com", so I'll have to be even more creative with the rest of the URL.
Use meaningful abbreviations, consistently. Better still, avoid abbreviations altogether by using short words in preference to long ones (eg "shows" instead of "exhibitions"). If you must abbreviate, use meaningful acronyms (eg "pr" for "press releases") and easily decipherable shortenings (eg "conf" not "cnfcs" for "conferences"). Of course, you can only follow this advice if you haven't already built your site, because changing URLs once visitors have got used to an established pattern is a definite no-no. Similarly, once you've adopted one abbreviation, it's not a good idea to confuse visitors by using alternative shortforms of the same word.
Consider using two URLs. If you can't avoid having a long URL, you might want to consider offering a shorter alternative that redirects to the original. But use this carefully, as search engines don't like being redirected, and visitors will be confused if it's not clear which version they should be using to locate the page. [UPDATE added 12/26: There's a useful SitePoint article, Search Engine-Friendly URLs, which discusses Apache's ForceType directive. This is a useful tool to have in your armory for keeping your URLs short and meaningful.]
Break up long URLs with hyphens. Most email clients will wrap text at a hyphen without inserting a line return, so if you can include a hyphen before you get to the 75-character limit, you should avoid cut-and-paste problems. But visitors still won't enjoy dictating the URL over the phone, or typing it in from a newspaper article.