Duplicate content is content that is found on a website that is similar, or may even be identical, as that of another site on the Internet. If the content of an article or blog is an exact match, then it is considered to be duplicate content. Oftentimes, duplicate content is unintentional, but sometimes it is done on purpose so as to manipulate search engine rankings, and redirect traffic to a specific site. It can be noted that the same article written in a different language is, however, not considered duplicate content.

Here are 10 Reasons why duplicate content may harm your Google rankings:

1. Duplicate content is considered a type of search engine spam, where you repeat a search term (word or phrase) as many times as possible on a website or in a document. This may harm your rankings with Google.

2. If a website lists the same page hundreds of times, only changing a few words so as to attain high ranking on various keywords, the website is producing duplicate content.

3. Another type of duplicate content that should not be used revolves around affiliate programs. High-traffic websites establish affiliate programs and sometimes these affiliate programs take a template and offer that template to its own affiliate base, so there are many websites on the internet offering the same things. Google feels this is not offering anything of great value to the web community and doing such things can get the website de-listed by Google.

4. Do not create a website that is filled with third-party content, since you will not rank high in the Google index by doing this-you may even get de-listed or banned.

5. Google, and search engines in general, are always looking for cataloging and gathering quality content, so try to have unique content on your site.

6. Do not rely on duplicate content to drive traffic to your site, since it may do exactly the opposite, and you will be de-listed if you do this. Be careful if you are integrating RSS feeds and automated content into your site. What looks smart today may not always be smart in the future.

7. If you don't rewrite the title tags on your website, which are still a major way to get to a search engine, you may get de-listed by Google. Most CMS and Blogging tools does have this options.

8. If your content is not unique and you have used too many emphasis tags such as, "h1," "h2," "b," and so on, then the chances of getting de-listed (loosing SERP rankings) are pretty high.

9. You need to rewrite your Meta descriptions. Meta description is essential when it comes to getting targeted traffic from search engines as well. Keep it below 160 letters. When it comes to duplication, they are a sure cue for search spiders, and so they may harm your Google ranking.

10. Do not repeat text in your article or blog. Google and other search engines want clean content that is not simply a repeat or copy of what others have already said.