Good Luck. : )

Also keep in mind that just because links exist somewhere doesn’t meant that those links have SEO value. It is always possible that Google will disregard or devalue links that appear to be manipulative.

Here I want to ask one more question, that, several of so called SEO experts distribute 1000s of copies of an article, rewritten (by hand or by using some software) at word level or sentence level or paragraph level into 1000 different articles and submit them to different websites. Most of the SEO services being sold in the markets involve submitting many copies of rewritten articles with a backlink inside. If Google is smart enough to sort out these practices, why do they are encouraged by improvements in SERP’s and many of their backlink pages being indexed by google.

Actually the engines are fairly good at identifying instances of partial duplicate content too. It’s not too difficult to determine if various chunks of text have been reordered on a page, or if X% of the content between two pages is the same.

Here’s some complicated stuff from Stanford you might be interested in:
http://nlp.stanford.edu/IR-book/html/htmledition/near-duplicates-and-shingling-1.html

This topic was also touched on at an SES session this year:
http://www.seroundtable.com/dup-content-sessanfran2011-13832.html

And for some more recent information on duplicate content I’d recommend:
http://www.seomoz.org/blog/duplicate-content-in-a-post-panda-world

Here my curiosity lies in the fact that how search engines can possibly distinguish two articles to be similar or not similar if they are not exactly the same. I mean how much intelligent the search engines can be to decide whether an article is rewrite of a given article or not.

The engines avoid providing percentages or specific formulas for what constitutes duplicate content. This is in their best interest, as revealing that information would make it harder to prevent abuses.

I think a good rule of thumb is, ‘Would users consider these two pages to be essentially the same article?’ If so, there’s a good chance that the engines will too.

In terms of rewriting or reworking content, a good approach is to summarize key points and/or quote select passages and then add your own take or spin to it. In this way you are adding value for users, which in turn makes the content more valuable and less likely to be filtered as duplicate.

Thanks for the advice about duplicate content. I agree that attribution links are vital, and I recommend not posting all the content

Do you have any information on how to tell when an article is considered duplicate? In other words how different does text have to be to be considered different?

The good folks at google state “Duplicate content generally refers to substantive blocks of content within or across domains that either completely match other content or are appreciably similar.”

What if 5 out of 500 words are different? 5 out of 50? Is being “appreciably similar” defined by some mathematical formula – say for example “the percentage of words that are the same in a given text exceeds 75%?”

On a related note, if an article or press release is supposed to be posted on several locations, what’s are some rules of thumb for rewriting the text in such a way to avoid it from being considered duplicate content?

Great post ! From a publisher perspective if we give a live link (do follow) to all articles/news websites.Then don’t you think we will pass our own link juice (Value) to those websites. Giving away 1/2 links is ok, but when you are syndicating content through out year, you will end up with thousands of out bound links (one way )!! Don’t you think it will de-stabilize the whole website architecture in google and then you may loose everything things!!

** assuming use of no follow is out of question.As google strictly say – you must have to give a do follow link if you are syndicating content from other website. ***

Content Syndication is like a double edge sword. It is going to hurt you from either side. What you say?

Regards
Rahul