When you are link building for your site, you need to make sure that the content those links appear on is high quality, unique content. That just makes good sense.
Another good reason to make sure that every page linking to yours is unique is that Google is what’s called a “full text search engine.” What that means is that Google breaks down content into the words and phrases that it’s made up of, and catalogs all of those keywords in an index.
Then, when somebody performs a search, it looks through that index and finds pages that are related to the keywords being searched for. If your page is one of them, and the other quality factors are in place (like links to the page), then Google shows that page in the search results for the keywords.
That means that if all of the pages that link to your site are the same, then all of the keywords that get put into Google’s index for those pages will also be the same, which seriously limits the probability of your linking pages popping up in the search results.
For instance, let’s say you doing some article marketing and post the same article to 100 sites, and that article contains 10 phrases that Google considers important enough to put into its index. That gives you 10 keyword phrases that all 100 of those linking pages have a chance of showing up for in the search results.
On the other hand, let’s say you distribute a unique article to each of those 100 sites. If each one of those articles contains 10 different phrases that make it into Google’s index, that gives you 1,000 keyword phrases that your linking pages have a chance of showing up for.
If each unique article can deliver only one new visitor per day, then all 100 duplicate articles would only deliver 30 visitors a month (because remember, Google will only show one of those pages in the search results). On the other hand, if you have 100 unique articles each delivering one new visitor per day, that’s 3,000 new visitors per month.
Start multiplying that out by 1,000 articles, or 10,000 articles, or even 100,000 articles, and you begin to see why unique content is so valuable.