There are a variety of "free and easy tricks" out there, which are supposed to provide your site with free unique content. Some of these methods include RSS feeds or copying articles from article directories. However, while this content might be unique to you, it is not unique to Google.
RSS feeds, for example, are only recycling the same news headlines and summaries that originated from the site where the RSS is getting it's content. Therefore, you are getting a truncated portion of another site's content, which Google has already indexed. Since Google has already indexed this text, the search engine will recognize the fact that your content is not unique and will therefore exclude your content from any search results. In fact, using duplicate content may have a worse effect on your status with Google than just a page or two not getting indexed -- once the search engine recognizes that your site contains a lot of duplicate data, this will have an overall negative effect on your search engine rankings.
The same thing is even more obviously true with articles that you copy and paste onto your blog or website. This content has long ago been indexed by Google and will thus not at all help your online marketing efforts.
Google also recognizes duplicate Twitter content.
So how can you avoid using duplicate content on your website or blog? You can utilize the automated rewriting power of Spinbot.com.
Spinbot is designed to create new, human readable text out of any text you enter. Spinbot's algorithm recognizes a wide range of English idioms, which helps it to spin textual content accurately, in such a way that it will not come out sounding like gibberish.
The best way to see what I'm talking about is to visit Spinbot right now and start generating all the free unique web content you will ever need!