1) Keyword stuffing. This involves using a keyword too often across a particular web page (and yes meta data does count). The big three search engines (Yahoo, Bing and Google) all have slightly different approaches to how often you can use a keyword. As a general rule, if web page copy doesn’t read very well and you notice the same word or phrase too often you’ve probably got the balance wrong.
2) Invisible text. This can be done either by using the same colour font and page background (either page by page or via the CSS) or by using tags in the code inappropriately. Either way the only real content that matters is that which the users can see.
3) Cloaking. This is the generic term given to a website that changes the way pages are viewed (depending on who is viewing them). For example one technique is to create pages that visitors to a website will never see. They are designed specifically to be read by the search engine spiders. The user will never know they exist but the aim is that the search engines rank the page regardless. Then, when that page is found by a user they are redirected to the page the website wants the user to see.
4) Link farms. These are usually groups of websites that all link to each other to benefit from the kudos and importance Google (in particular) awards to in-bound links.
5) Doorway pages. These tend to contain very little content (so already off to a bad start) but rank on the basis of the meta data and the keywords that are used.Tags: SEO