Every time I go to a Search Engine Strategies show I hear at least half a dozen audience questions about duplicate content. What is it, what happens if you have it, how do search engines discover it and so on... Apparently the folks at Google noticed this question popping up at the show well because they've decided to offer up some input on duplicate content via their blog. If you're still wondering about this issue yourself, here's a great chance to hear it straight from the horses mouth.

Google offers up a pretty simple definition of what they consider to be duplicate content:

Duplicate content generally refers to substantive blocks of content within or across domains that either completely match other content or are appreciably similar. Most of the time when we see this, it's unintentional or at least not malicious in origin: forums that generate both regular and stripped-down mobile-targeted pages, store items shown (and -- worse yet -- linked) via multiple distinct URLs, and so on. In some cases, content is duplicated across domains in an attempt to manipulate search engine rankings or garner more traffic via popular or long-tail queries.

They also offer up a handful of suggestions to keep your site from running into any duplicate content filters. The suggestions range from simple (use your robots.txt file appropriately) to more complex (proper syndication and CMS techniques) and will go a long way toward helping you keep your own site free and clear.