There are many methods that webmasters use o ‘trick’ search engines into listing their pages at a god position on SERPs. Such a position, however, usually does not last long.
The first method is called keyword stuffing. It involves overusing keywords on the page. Webmasters will simply repeat keywords at the bottom of the page where visitors can’t see them. Or they might use invisible text (text in the colour matching the background colour). The page visitors would not catch the words, but the spiders that visit the page surely do (spiders read page content in HTML code and not in text). In fact, some search engines have gone a step ahead. They have spiders which can identify and ignore text that is the same colour as a page’s background.
A common tactic that was used at one point was using keywords that are not related to the content of the page at all, but are the most popular. This method did provide limited success, until spiders got even smarter and found a way to check keywords and meta tags with page content.
Webmasters have proven to be very innovative in other different ways. For example, webmaster creates a simple page that includes key words to get listed on an SERP. That simple page has a program that redirects visitors to a different page having nothing to do with the original search term. In this way, the webmaster creates several pages with keywords of all the popular terms and can get a lot of traffic to a particular site.
A second category of methods that are black hat SEO techniques is called page stuffing. Webmasters create two exact web pages, with the same content. He hopes that both pages will make the top SERP results. With many pages of the same content, the webmaster ends up pushing other pages off the top of the SERP and eliminates any competition. Now, many search engine spiders can compare pages against each other and determine if any two pages have the same content.
A third black hat technique is called selling or farming links. We have established that search engines look at the links of a page to determine the page’s relevance and hence, rank. SO some webmasters buy links from other sites to boost its page’s rank. This is what a link farm is; a collection of web pages that interlink with each other to increase a page’s rank.
Some link farms can have hundreds of web sites, each with a web page just to list the links of every other site in the farm. If a search engine discovers a link farm, it will flag every single site in the farm, or might even demote every page’s rank. In extreme cases, it can ban all the sites from its indexes.
We see that search engines usually do figure if a particular site is using one of the above black hat techniques to increase its SERP position. Cheating the system in this way might lead to a temporary increase in visitors, but besides the benefits being short-lived, most search engines penalize Web pages for using these techniques.