With Facebook's new "graph search" function, your friends can now more easily find out stuff about you.
He says that Graph Search is "privacy aware." "Most of the things people share with you isn't public" and that the new search tool knows what to show and what to hide.
He says that Facebook has dedicated considerable computing resources to protect your privacy.
"About 10 percent of our computation in our data centers is privacy checks. No other company in the world has infrastructure like this," he says.
Ten percent might not sound like a lot, but in terms of raw computing power it is. Facebook is one of busiest sites on the Internet and has built a massive technical infrastructure to support its rapid growth. This includes three massive data centers built from scratch, plus space leased from about a half a dozen other sites.
Although Facebook doesn't say how many servers it owns, we know it uses tens of thousands of them and has spent more than $1 billion on its infrastructure in 2011.
Even so, making sure that only your friends can see your posts and photos on Facebook isn't easy, even without the search function. Even Mark Zuckerberg's sister, Randi, didn't get it right when a photo she thought she was sharing with just a few people wound up publicly visible.
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