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Lesson 7Search engines
ObjectiveDescribe the function of search engines.
The Web provides users with immeasurable amounts of information. In order to be able to leverage that information for either personal or professional use, users need assistance in searching that information. That's where search engines come in. Search engines like the kinds available on Internet portals[1] like Yahoo! or msn process vast quantities of information to make the Web or an individual site useful to a user.

Discussion

What do you think are the most effective search engines on the market today and why?
Answer:

How search engines work

Typically, a search engine works by processing a user request such as a keyword or question. It sends out a spider[2] to fetch as many documents as possible. Another program, called an indexer[3], then reads these documents and creates an index based on the words contained in each document. Each search engine uses a proprietary algorithm to create its indices such that, ideally, only meaningful results are returned for each query.

This illustrates how a search engine works.
The diagram above illustrates one of the processes within a search engine.

Search engines on an eBusiness site

Several companies specialize in developing search engines for eBusiness solutions. Why provide a search engine for your site? A search engine provides users with a key tool to navigate through your site's content. In the majority of cases in eBusiness, it is only necessary (when applicable) to purchase and tune one search engine. Some of the providers sell their engines in programmable components, enabling eBusiness developers to apply search capabilities in a customized fashion. There are good reasons to customize your search capabilities, whether you're working in a B2B or B2C environment:
  1. The ability to customize the use and implementation of a search engine for a particular eBusiness solution may be particularly useful for B2B implementations where the types of content that might be searched are limited and known.
  2. Even in B2C solutions, the site developers may want to limit the type of content search, and to be able to display search results in a "sticky" fashion.
The next lesson wraps up this module.
[1] Portals: A Web "supersite" that provides a variety of services including Web searching, news, white and yellow pages directories, free e-mail, discussion groups, online shopping and links to other sites. Web portals are the Web equivalent of the original online services such as CompuServe and AOL. Although the term was initially used to refer to general-purpose sites, it is increasingly being used to refer to vertical market sites that offer the same services, but only to a particular industry such as banking, insurance or computers.:
[2] Spider:A program that automatically fetches Web pages. Spiders are used to feed pages to search engines. Spiders are also called Web crawlers and PriceBots.
[3] Indexer: A program that reads the documents fetched by a search engine spider then indexes it according to the words used in the document.