As have Web site operators, who have accepted that they can never really know what information resides on their own sites, much less locate it and present it to site visitors. In addition, keyword based search engines are limited and one dimensional, unable to provide any real context for the information they present in response to queries. Directories, which are based more on the actual content of Web pages, are an improvement over keyword search, but have their own limitations. Because current directories rely heavily on human editors, the sheer volume of pages on the Web dictates that they will continue to fall farther behind in their ability to present a picture of the whole Web, or even a small part of the Web. In addition, many pages evolve over time as content is edited and changed, forcing the subjects of those pages to shift as well.
Manual classification is thus a non-starter.
In fact, they are far from automatic. This requires significant, ongoing investment in time and people to find representative documents to calibrate the classification mechanism to construct the desired topic taxonomy . Furthermore, as content breadth, complexity, and interconnectedness increases over time, these more aptly labeled semi-automated technologies' ability to accurately classify new and existing documents breaks down. While it's old news that the Internet is a powerful medium, not everyone realizes the full potential it offers for reaching people in ways that are unavailable with any other medium. The concept of contextual commerce, for instance, is a powerful one.