A cheap SEO technique where the same article is rewritten, using synonyms or by changing the word order in the sentence. In this way, many articles are created in hopes Google won’t flag them as duplicates. These articles are them posted all over the web and link back to the original. It is a risky black hat SEO practice now done with various software.

As a disclaimer, writers often spin content in their articles to reduce the similarity ratio, but if this is done for only a small portion of your content and you are only posting it once, you have nothing to worry about.