Question: I’m worried about duplicate content on my site. If I place a blog post on multiple sites, is that going to harm my search rankings? Will it be marked as spam?
Placing a piece of content on multiple sites isn’t always a good idea, but not necessarily for the reasons that you might think. There is no such thing as a duplicate content penalty. Google does not penalize sites for having duplicate content. And Google does not consider duplicate content spam.
Google does take action against sites that seem solely scraped from another site; in effect, the entire site is a duplicate of another site. But that’s really another issue entirely, and not likely to be one that you will casually encounter.
I occasionally see marketers avoiding quotations out of a misguided fear that it will show as duplicated content. Google looks for pages that are identical in content, not paragraphs of quoted content — so this is unnecessary. There are many situations in which a quote can be used to add value to content, so this would be disingenuous on Google’s part.
So why is it bad to have duplicate content? Google will generally combine multiple copies of a page into a single entry, and the entry that has the greatest PageRank will be the only one shown. So it’s not really bad for SEO, it’s just kind of pointless. The other listings will only be shown if the user specifically asks to be shown all the listings, which really only happens when someone is desperately searching for an obscure tech support issue.
But it is bad for the overall user value of a site to have multiple pieces of entirely duplicated content, so that’s something that needs to be considered. For the most part, a carefully curated outbound link is probably more usable and useful.
Answer: Duplicate content being considered “spam” is actually a myth. Duplicate content does not lead to any site-wide penalties. Google will group together duplicate content in the search engine page, so it isn’t great for SEO on an individual basis, but it doesn’t hurt the domain.