There are those that get on the computer one night and find that all of their Web pages have disappeared from Google. While others are still in the search engine index, but don't rank high for anything, not even for their Web site's name. It's a web site owner's worst nightmare, getting kicked out of the search engines.

Ultimately, many webmasters had little or no warning that this was going to happen. Many webmasters are left with no idea why they were kicked out and are left wondering how to get back in Google's search engine. There could be any number of reasons why a web site is banned by Google. The most common reasons for being banned are listed below in this article.

1. Duplicate Content
This is when multiple Web pages have the same content. Usually Google will just give a penalty to the Web page for this, where the page won't rank very high for the keywords in that web page, but there have been cases where complete Web sites were banned because they had too much duplicate content. You should make sure there is no other web site using your content.

To check for duplicated content simply search with unique phrase on your web page. If you find a Web site that has stolen your content you should contact the site owner and tell them to take it down or face legal action. Also, for copyright violations visit www.google.com/dmca.html and notify them that someone is infringing on your site's copyright

2. Cloaking
These are web pages created just for search engines. Cloaking delivers one version of a page to an Internet user and a different version to a search engine. Cloaking web pages are created to do well for particular keywords. There are various ways to deliver cloaking web pages. Each search engine's spider has an agent name, the cloaked page is than only delivered to the spider with the user agent name that was chosen.

You can also deliver cloaked pages to the search engines by IP address, but Google and other search engines say they can detect cloaking. There are other reasons to use cloaking, such as custom language delivery and geotargeted advertising.

3. Hidden Text or Hidden Links
This is text or a link that is invisible to the naked eye on a Web page, but are seen by spiders. Search engines use to have a hard time spotting this technique, but now days you should avoid doing this because Google and other search engines can spot this easily. Even if a search engine doesn't spot your hidden link, a competitor might find it and report your site. Sometimes this can be done without even knowing, so you better double check each Web page that you have messed with in the past few weeks.

4) Keyword Stuffing
Keyword Stuffing is when you load a Web page up with keywords in the Meta tags or on the Web page's content. The General techniques today for keyword stuffing are repeating the same word(s) over and over again in the Meta tags or on the Web page's content or using invisible text, as we talked about up above in this article. If the word is repeated too much it will raise a red flag to the search engines and they likely will place a Spam filter on the site.

5) Linking to Bad Neighborhoods
Bad neighborhoods are designed to increase your Web site's ranking or is Web site's using Spam techniques to increase search engine ranking. You should not link to any Web page that uses Spam techniques to increase ranking. You also should not join link exchanges that are designed to improve ranking or Page Rank. If you are not aware of linking to any Web site like this, you should check each outbound link on your Web site.

6) Buying Links for Search Engine Ranking
This where a Web site owner buys links just to increase his or her ranking. This is also used to increase Page Rank. Google and other search engines still have a hard time detecting this, but they are starting to catch on to this technique. If Google is aware of the site, they can just discount the Page Rank, so they can't pass Page Rank on.

7) Machine Generated Web sites
This is a site that generates hundreds of web pages that are basically the same page repeated hundreds or thousands of times, but with a few unique lines of text and unique title. Often times, search engines can't spot this, if done right by the site owner. However, if a spider doesn't spot your machine generated web pages, a competitor might find it and report your web site.

What to do after you are Spam clean?
Once you have cleaned up your Web site, you can try contacting Google by visiting www.google.com/contact/. Tell them that you made a mistake and won't do it again. Even if you do contact Google, they most likely won't let your Web site back in. If you happen to get back in, you need to keep your Web site squeaky clean because you probably will not get another chance.

If you can't get in touch with Google, I suggest that you wait for a few months after Google's spider visits your Web site and see if you get your ranking back or at least where you can see that your ranking is going up in the search results. During this time you should not change your Web site around much and give the search engines time to spider your Web site.

I really don't think that many Web sites have dropped because Google is penalizing them. Instead, I think Google has changed the factors or adds more weight to a factor(s) that they use to rank Web sites in the search results. All search engines make periodic changes to the way they rank Web sites in the search results, so don't be surprised if one week you rank number one and the next week you rank 30TH.