The Internet and The World Wide Web
ž Many people use the terms Internet and World Wide Web (aka. the Web) interchangeably, but in fact the two terms are not synonymous. The Internet and the Web are two separate but related things.
ž The Internet is a massive network of networks, a networking infrastructure. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. Information that travels over the Internet does so via a variety of languages known as protocols.
ž The World Wide Web is a way of accessing information over the medium of the Internet.
ž It is an information-sharing model that is built on top of the Internet. The Web uses the HTTP protocol, only one of the languages spoken over the Internet, to transmit data.
ž The Web also utilizes browsers, such as Internet Explorer or Firefox, to access Web documents called Web pages that are linked to each other via hyperlinks.
ž The Web is just one of the ways that information can be disseminated over the Internet.
ž The Internet, not the Web, is also used for:
ž e-mail, which relies on SMTP (simple mail transfer protocol)
ž Usenet (worldwide bulletin board system) news groups
ž Instant messaging and FTP (file transfer protocol; works the same as HTTP).
ž So the Web is just a portion of the Internet
Search Engines...
ž A ‘search engine’ keeps indexed records of all the web pages that can be accessed via hot links.
ž It is a software system that is designed to search for information on the WWW
ž There are three major types of search engines:
¡ Crawler-based search engines
¡ Human-powered directories
¡ Meta-search engines
ž Crawler-based search engines create their listings automatically by using a piece of software to ‘crawl’ or ‘spider’ the web and then index what it finds to build the search base.
ž They are good when you have a specific topic in mind and can be very efficient in finding relevant information in that situation.
ž Examples include:
¡ Google
¡ AllTheWeb
¡ AltaVista
ž Human-powered directories depend on human editors to create their listing. Typically, webmasters submit a short description to the directory for their websites, and these manually edited descriptions will form the search base.
ž They are good when you are interested in a general topic of search.
ž Not an efficient way to find information when a specific search topic is in mind.
ž Examples include:
¡ Yahoo directory
ž (Yahoo also provides crawler-based results)
¡ Open Directory
¡ LookSmart
ž Human-powered directories depend on human editors to create their listing. Typically, webmasters submit a short description to the directory for their websites, and these manually edited descriptions will form the search base.
ž They are good when you are interested in a general topic of search.
ž Not an efficient way to find information when a specific search topic is in mind.
ž Examples include:
¡ Yahoo directory
ž (Yahoo also provides crawler-based results)
¡ Open Directory
¡ LookSmart
ž Meta-search engines transmit user-supplied keywords simultaneously to several individual search engines to actually carry out the search.
ž Search results returned from all the search engines can be integrated, duplicates can be eliminated and additional features such as clustering by subjects within the search results can be implemented by meta-search engines.
ž Meta-search engines are good for saving time by searching only in one place and sparing the need to use and learn several separate search engines.
