Examples of spamming include excessive repetition of a keyword in a page, optimizing a page for a keyword which is unrelated to the contents of the site, using invisible text, etc. Most search engines will penalize a page which uses spamming. Also called spamdexing. In a different context, spamming is also used to mean the practice of sending unsolicited bulk email. A software that visits web sites and indexes the pages present in those sites.
Search engines use spiders to build up their databases.
The spider for AltaVista is called Scooter, the spider for Excite is called ArchitextSpider, the spider for Northern Light is called Gulliver. A word that often appears in pages, yet has no significance by itself. Most search engines ignore stop words while searching. The contents of the Title tag is generally displayed by the browser at the top of the browser window. The search engines use the Title tag to provide a link to the sites which match the query made by the user.