As the title suggests, the site is now going to be visible to members only. This isn’t a huge deal as registration is free http://www.blackhat360.com/forums/register.php
We’re going to be adding several scripts and code samples along with regularly updated articles and content, so check back often and tell some close friends.
That was some extended vacation. I must apologize for the lack of recent blog posts. Between the holidays, and the hectic schedule we’ve kept over the past couple months, i’ve completely ignored this palce. Lets not make a habit of that 
Stay tuned for some new content and artciles.
Brian
Yesterday we discussed the HOW portion of detecting duplicate content. Today I want to get into the actual process itself.
A wide spread Theory in the SEO world states that duplicate content not only carries a heavy penalty, but in fact can and will lead to a domain being banned or deindexed. Today I am going to discuss why I believe that this is not only unfounded, but perhaps completely untrue.
Lets start with some facts and figures. I’ve had the pleasure of reading dozens of research papers from msn, yahoo, google, and other leading members of the academic and professional search arena. From these papers it’s easy to determine that duplicate content detection is entirely possible in theory and at least partly in practice, but I believe the “practice” portion is where almost everyone may be wrong.
So what would it take for the big G to pull off duplicate content testing in the real world? Well, lets start by looking at the numbers. Lets assume it’s still 2004 and google still has “only” 8 billion pages in their index. Estimates show that they have several PETABYTES of data across their datacenters. So i’m joe webmaster and I put up a page about sprinklers. Does anyone here really believe that Google or anyone else on this planet actually has enough computer processing power to take my single page about sprinklers, shingle it and compare it to their other 7,999,999,999 pages of content each of which needs to be shingled as well? Shingling as we discussed yesterday, is the process by which search engines determine unique content from duplicate content. Of course, you do have the problem of it being a very intensive calculation because you’re not comparing A->B you’re comparing every document against all other documents. I think they call this a O(n2) problem. and it happens to be a very expensive process cpu time wise. Unless a page is flagged to begin with, it would be cost and time prohibitive to carry out such an expensive calculation on every page in their data set.
So if this is the case, what is duplicate content used for? What is the scope of the data google is looking for? I believe they check for duplicate content on a PER DOMAIN BASIS, meaning they take a single domain, check the content and run comparisons to give the overall domain a content quality or duplicate content quality score. Lets see why that makes sense on several levels. First, it’s within the ability of their crawler to do such a thing from a cpu processing power perspective, it also makes sense that they would factor this into the overall quality score for a domain.
Now the evidence:
1) A year ago I put up a 100 percent clone of wikipedia. I used the wikipedia template, I copied the data from their database, etc. This new domain was 100 percent identical to that of wikipedia.com.
The result? I rank well for thousands of terms, the domain has almost 1 million pages indexed in google, and it receives 3-5K uniques per day. So much for a duplicate content penalty. Of course the content is highly unique from page to page on the domain, but it isn’t unique when the scope is expanded to include the entire internet.
2) PublicBlend.com - By definition all social media sites contain 100 percent duplicate content that would never pass a shingling algorithm. All of our stories come directly from other web pages. In fact they are direct copies of articles from all over the internet.
The result? PublicBlend.com has been steadily growing in search engine traffic every month and now receives over 3,000 uniques a day from google alone. (we recently changed the domain name, so the indexing has started over)
3) News sites, not just social media, but regular news media as well. Reuters is the source for 90 percent of the news on the net. Everyone duplicates their stories word for word yet they all rank well for the resulting stories.
I hope the above sparks some debate and discussion on the topic of duplicate content. It may also raise some other interesting questions:
From a white hat perspective, what happens when 50 spam sites scrape your feed? Will your content get penalized or will the spam sites get penalized? How would a search engine determine who wrote the article first? Would they simply rely on domain trust? If so that opens the door to all sorts of gaming options using old trusted domains.
I’ve read seemingly hundreds of forum posts discussing duplicate content, none of which gave the full picture, leaving me with more questions than answers. I decided to spend some time doing research to find out exactly what goes on behind the scenes. Here is what I have discovered.
Most people are under the assumption that duplicate content is looked at on the page level when in fact it is far more complex than that. Simply saying that “by changing 25 percent of the text on a page it is no longer duplicate content” is not a true or accurate statement. Lets examine why that is.
To gain some understanding we need to take a look at the k-shingle algorithm that may or may not be in use by the major search engines (my money is that it is in use). I’ve seen the following used as an example so lets use it here as well.
Let’s suppose that you have a page that contains the following text:
The swift brown fox jumped over the lazy dog.
Before we get to this point the search engine has already stripped all tags and html from the page leaving just this plain text behind for us to take a look at.
The shingling algorithm essentially finds word groups within a body of text in order to determine the uniqueness of the text. The first thing they do is strip out all stop words like and, the, of, to. They also strip out all fill words, leaving us only with action words which are considered the core of the content. Once this is done the following “shingles” are created from the above text. (i’m going to include the stop words for simplicity)
The swift brown fox
swift brown fox jumped
brown fox jumped over
fox jumped over the
jumped over the lazy
over the lazy dog
These are essentially like unique fingerprints that identify this block of text. The search engine can now compare this “fingerprint” to other pages in an attempt to find duplicate content. As duplicates are found a “duplicate content” score is assigned to the page. If too many “fingerprints” match other documents the score becomes high enough that the search engines flag the page as duplicate content thus sending it to supplemental hell or worse deleting it from their index completely.
My old lady swears that she saw the lazy dog jump over the swift brown fox.
The above gives us the following shingles.
my old lady swears
old lady swears that
lady swears that she
swears that she saw
that she saw the
she saw the lazy
saw the lazy dog
the lazy dog jump
lazy dog jump over
dog jump over the
jump over the swift
over the swift brown
the swift brown fox
Comparing these two sets of shingles we can see that only one matches (”the swift brown fox“). Thus it is unlikely that these two documents are duplicates of one another. No one but google knows what the percentage match must be for these two documents to be considered duplicates, but some thorough testing would sure narrow it down ;).
So what can we take away from the above examples? First and foremost we quickly begin to realize that duplicate content is far more difficult than saying “document A and document B are 50 percent similar”. Second we can see that people adding “stop words” and “filler words” to avoid duplicate content are largely wasting their time. It’s the “action” words that should be the focus. Changing action words without altering the meaning of a body of text may very well be enough to get past these algorithms. Then again there may be other mechanisms at work that we can’t yet see rendering that impossible as well. I suggest experimenting and finding what works for you in your situation.
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