Duplicate content is copied content from other websites. Do not use such content as it not good for Excellent user experience. Duplicate titles, and meta descriptions are also harmful for information and your site. If you write an article and submit it on many other blogs or sites then it is also termed as duplicate content. So do not share same content over the Internet. It misleads information.

When two pieces of content exactly match the same then it becomes a duplicate content.

When two blocks of content becomes the same then it is duplicate content.

you content is already placed anywhere in another website

Duplicate content means not original, it is copied content. This is not good for any website.

Same content which appears on other website !!

Duplicate content
 

If you are using the same content whose already live on the internet then content coming in duplicate.

Duplicate content defines that same content already running on Google search engine result page, called duplicate content.