What is metadata again? The term "metadata" refers to the information that is used to "tag" other information. It is data about data. Huh? All right, here's an example - When researchers submit their scientific papers for publishing, they have to submit a list of keywords along with their papers. These keywords are an example metadata. Another example of metadata is the information a library puts in cataloging system.
Today, on the Internet people are putting in a variety of metadata in a variety of formats. Yet, most data remains hidden to us. There is a very simple reason for that – lack of knowledge about the vocabulary of the metadata. This is a problem we face more often when searching for more specialized information like medical or scientific information. Lack of knowledge about the metadata can really stifle the accessibility to the data.
One of the ways the problem today is handled in via faceted search. Faceted search just means a search that uses classification categories. Do you recall the initial Yahoo! that worked like a directory with subheadings like "education", "entertainment", etc.? That is a pretty good example of faceted research. The fact that the approach failed, especially post-Google, is a good indicator of the problem with this kind of approach. One of the key problems Yahoo! had was that the user didn’t want to waste time digging five layers deep in to find something. Another problem was that the categories just weren’t clear for some users, especially as they got deeper. Then there was the problem that sometimes information doesn’t belong to the intuitive category but to an arcane category that nobody knows. Let me boil down the last point – Yahoo!’s categorization system assumed that you knew something about the term you were searching for and hence could pin down where it would be in the tree. If you didn’t know anything about the term, then the task of finding an object via a classification system is virtually impossible.