What is a keyword, exactly? It can simply be any word on a webpage. For example, I used the words radar gauges in a entence, making it one of the keywords for this particular webpage in some search engine's index. If the words radar gauges are in the subject of this webpage, it is a very useful keyword. Those keywords would actually tell a user something about the subject and content of this page.
The information seeking process to find radar gauges on the Web is fairly similar and notably different with classic searching in the classic information retrieval systems or pre-web online systems. It is similar because both are computer based and dealing with electronic information. However, it is considerably different because potential users and information sources in the Web environment are very different with pre-web online information systems.