If you have a website that has two or more URLs with the same content, that is duplicate content.
If you have two or more website that have the same content, that's also a duplicate content.
So, why is it so bad to have duplicate content, you may asked.
Well, for one, Your webpages might get penalizes by Google.
So How to fix this problem ?
If you have a website that has two or more URLs with the same content you can use what they called Canonical URL Link Tag. But pay attention. This thing only woks for google.
This tag will let Google know that you want a page to be considered the official address for the content created.
For example how to fix this problem.
"mysite.com/index.html" and "www.mysite.com/" and "www.mysite.com/index.html" might be considered three pages by googlebot because it creates "link dilution" and Googlebot might index the pages lower because of it.
Okey, here is how to use canonical URL :
* For HTML pages:
<link rel="canonical" href="http://www.mysite.com/correctpage.html">
* For XHTML pages:
<link rel="canonical" href="http://www.mysite.com/correctpage.html">
Don't forget to replace the "mysite.com/correctpage.html" with your own sites name and page you want to be the official page. After that you want to copy and paste the link into the head section of your website where the meta data is located. This way, google will know that this is the page you want Google to index.
That the first type of duplicate content and how you can fix it.
Now, the second type of duplicate content is where you have two or more websites that have the same content.
In this situation, googlebot will have to decide which of these sites deserves the credit for that content.
So, how do we fix this ?
Well, you can use these three neat tricks to generate different versions of an original content:
1. Use a different headline.
2. Replace paragraphs and sentences around.
3. You can Use less bullets in your modified version.
I recommend to use all these tricks together.