SEARCH ENGINE- It is a program that searches a document for specified keywords and return a list of the documents where the keywords were found. It works by sending out a spider to fetch as many documents as possible.
Yahoo is the web's oldest 'directory' where human editors organize web sites into categories.It has both human-edited directory and a spider based index provided by Google. Sponsored results are provided by overture and appear at the top of the results page and additional entries are presented at the bottom of the page whenever a next page is available. It classifies information under a series of major subject headings and then sub-dividing these into a more specific headings. The web sites that correspond to these headings are listed as appropriate in this directory structure.
ADVANTAGE- It is excellent and easy to navigate subject catalogue. The subject heading and sub-headings can be used to guide the user through vast amount of information until they find what they are looking for.
DISADVANTAGE- Directories are far more cost and time intensive to maintain due to lack of scalability and the necessary human input to create such list and periodically check the quality of the listed websites.
Unlike highly automated search engines, Directories are manually complied taxonomies of websites.
References:
Sullivan,Danny.(Mar.14.2007).How Search Engine works .[Online].Search Engine Watch. Available from:
http://searchenginewatch.com/showPage.html?page=2168031 [Accessed 07/10/07].
Barlow,Linda.(updated 05/11/04).The Spider's Apprentice. [Online]. Monash.Available from:
http://www.monash.com/spidap3.html [Accessed 07/10/07].
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