For example, a student writing a dissertation might use del.icio.us to track all their source materials and commentary. Instead of having a hard-to-read list of bookmarks in a drop-down menu on their Web browser, users just consult their del.icio.us page to view their favorite Web resources, along with their own annotations.
To organize their bookmarks, del.icio.us users tag them with personalized keywords, like a folksonomy, instead of using a hierarchical taxonomy or set categories. This makes it easier for del.icio.us users to find relevant resources intuitively.
But here's the ultimate value of social bookmarking: the ability to share bookmarks with others, instantly tapping into collective wisdom. For example, let's imagine you want to learn about tropical fish. From the del.icio.us home page, you search for "tropical fish." Instead of finding only the most _universally popular _ sites Google shows you, on del.icio.us you find the _favorite _ resources of tropical-fish fanatics. These are the resources valued by the people with experience, the people who eat, breathe and sleep tropical fish.
Shared resources are the ones with real word of mouth, not just a certain number of links or brute-force advertising. The results are the best in the judgment of those who know the most. There's no substitute for recommendations by people who've consumed the content and found it important, useful or entertaining.
Search is what you do when you know what you're looking for. Discovery is how you find what you didn't know existed.