Whats the difference between a Search Engine and a Directory?
A Search Engine is an automated piece of software that trawls the WWW and comes in 3 parts. The ‘spider’ or ‘crawler’ visits web pages, abstracts information and deposits this in an ‘index’, a vast catalogue of all the sites visited. The third part of the engine is its sophisticated software which sifts through the millions of indexed pages to find matches to a search term and then rank them in order of relevance. Directories, such as Yahoo! however are vetted entirely by humans, and are organised in a hierarchical structure (which is how Yahoo! got its name – Yet Another Hierarchical Organisational Oracle!). Directories and Search Engines provide a very similar service, but operate in a very different way. It is much harder to get a good listing in a directory because of the human gatekeeper, and the problems they have just keeping up with the explosive growth of material on the WWW. On the other hand they are able to evaluate web pages more reliably.
