SEO: Crawling & Indexing
When most people talk about Internet search engines, they really mean World Wide Web search engines. Before the Web became the most visible part of the Internet, there were already search engines in place to help people find information on the Net. Programs with names like “gopher” and “Archie” kept indexes of files stored on servers connected to the Internet, and dramatically reduced the amount of time required to find programs and documents. In the late 1980s, getting serious value from the Internet meant knowing how to use gopher, Archie, Veronica and the rest.
Today, most Internet users limit their searches to the Web, so we’ll limit this article to search engines that focus on the contents of Web pages. Before a search engine can tell you where a file or document is, it must be found. To find information on the hundreds of millions of Web pages that exist, a search engine employs special software robots, called spiders, to build lists of the words found on Web sites. When a spider is building its lists, the process is called Web crawling. (There are some disadvantages to calling part of the Internet the World Wide Web – a large set of arachnid-centric names for tools is one of them.) In order to build and maintain a useful list of words, a search engine’s spiders have to look at a lot of pages.
How does any spider start its travels over the Web? The usual starting points are lists of heavily used servers and very popular pages. The spider will begin with a popular site, indexing the words on its pages and following every link found within the site. In this way, the crawling system quickly begins to travel, spreading out across the most widely used portions of the Web.
Curt Franklin “How Internet Search Engines Work” 27 September 2000.
HowStuffWorks.com. <http://computer.howstuffworks.com/internet/basics/search-engine.htm> 11 December 2016
Read also Week 7 ICT New Media – Website Concept
or go back to Week 5 ICT New Media – Computer Security