Finctionality of Internet

Search Engines

• A tool for locating Internet resources

Interactive

Database

Automated

Web search engine is an interactive tool to help people locate information available via the World Wide Web.

Web search engines are actually databases that contain references to thousands of resources. Users are able to interact with the database, submitting queries that "ask" the database if it contains resources that match specific criteria.

There are many search engines available on the web. A web search engine provides an interface between the user and the underlying database.

The interface presents the user with a place to type in a search string, which may be a word, a phrase, a date, or some other criterion, and a way to submit the request. The web search engine runs the search string against the database, returns a list of resources that match the criteria, and displays the results for the user.

Many web search engines use "fill-out" forms as an interface, and support complex queries. Many also include instructions and help in searching the database. Here is an example from the search engine AltaVistaTM:

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Because web search engines can use hypertext, users are able to link directly to resources listed in the results display. For example, here are some of the results from the previous query "DNA and cancer".

How do resources end up in a web search engine's database?

Most web search engines use automated tools and programs to gather resources. These tools, often referred to as worms, spiders, crawlers, and robots, search thousands of websites worldwide, collect information, and store the information in the database.

Each web search engine provides its own database, interface, and special features. A search engine's database cannot possibly contain every piece of information that is on the WWW, therefore search results will not include every available web resource.

In addition, because each search engine collects resources differently, the same query typed into several search engines is likely to produce different results.

A web search engine is an interactive tool that enables users to locate information available via the World Wide Web. Search engines provide "fill-out" forms and other interfaces so the user can type in a query, submit the request, and retrieve a list of resources that match the search criteria.

The hypertext environment makes it possible to offer a link directly from the list of results to the resources themselves. A single search engine cannot cover every available web resource, but many do contain references to millions of resources. Results may vary from one search engine to the next.