A lot of a web site's traffic is generated by search engines and directories, so it's obvious that web masters will do anything to ensure their site is listed at the top. There are different search engines, and I'd like to discuss some of them briefly.
Search Engines are index web pages based on content. Each engine worksdifferently. They base the search results on Meta Tags, page content, title, ora combination of these. They get their content from spider programs.
Directories categorize the WWW based on input submitted by a human being. An example is Yahoo. When someone searches for a keyword, this is referenced against a database of sites that contain a title and description for a particular site.
Spiders are used by a search engine to index the web. They all capture specific information about a page. Some capture the title and the first 1,000 characters of content. Some capture the title and "description" Meta Tag. Some look only for the "keyword" meta tag. Some use a combination of all of these.
How do search engines work?
They send out electronic spiders that make copies of the pages they find on the web, store them in an index, or an encyclopedy of web pages. When people search, search engine software flips through this book to find pages that seem to match what they are looking for. They look for the search words in the title, meta tags and beginning of documents they have indexed.