The social-­bookmarking site del.icio.us is a deeply influential site, credited by many for jump-­starting the immense amount of activity around tagging.

The main resources of importance in del.icio.us (http://del.ico.us) are bookmarks, that is, URLs. You can associate tags with a given URL and look at an individual’s collection of URLs and the tags they use. In this section, I again explain the URL structures by browsing through the site and noting the corresponding URLs.

You can look at the public bookmarks for a specific user (such as rdhyee) here:

http://del.icio.us/{user-id}

For example:

http://del.icio.us/rdhyee

You can see all the bookmarks of a user by tag here:

http://del.icio.us/{user-id}/{tag}

For example:

http://del.icio.us/rdhyee/NYTimes

You can see all the URLs that people have tagged with a given tag here:

http://del.icio.us/tag/{tag}

You can see just the popular URLs associated with the tag here:

http://del.icio.us/popular/{tag}

You can access today’s popular items here:

http://del.icio.us/popular/

You can access just the newest popular ones here:

http://del.icio.us/popular/?new

Correlating a URL to a del.icio.us page is a bit trickier. Consider the following URL:

http://harpers.org/TheEcstasyOfInfluence.html

which you can reference from del.icio.us here:

http://del.icio.us/url/53113b15b14c90292a02c24b55c316e5

So, how do you get 53113b15b14c90292a02c24b55c316e5 from http://harpers.org/TheEcstasyOfInfluence.html? The answer is that the identifier is an md5 hash of the URL. In Python, the following line of code:

md5.new("http://harpers.org/TheEcstasyOfInfluence.html").hexdigest()

or the following PHP code:

         <?php
          $url = "http://harpers.org/TheEcstasyOfInfluence.html";
          print md5($url);
         ?>
      

yields 53113b15b14c90292a02c24b55c316e5.

Note that the following:

http://del.icio.us/url?url=http://harpers.org/TheEcstasyOfInfluence.html

also does work and redirects to the following:

http://del.icio.us/url/53113b15b14c90292a02c24b55c316e5