Sometimes it feels like the internet's just the same thing over and over. Google agrees: According to the search giant, 25-30 per cent of everything online actually is a duplicate of something else somewhere else online.
On the GoogleWebmasterHelp YouTube channel that you didn't know existed, engineer Matt Cutts turns to the mailbag to answer a frequently asked question regarding how duplicate content affects a site's SEO. It turns out that Google doesn't see dupes — like blockquotes, reblogs, reposted images, etc — as spammy content. Instead, the mysterious Google algorithm groups all of the duplicated content into a single lump and attempts to surface the best of it.
How Google deals with duplicated content isn't all that surprising — it's just crazy how much of the information out there is just a copy of something else. [Search Engine Roundtable]