Facebook users post more than 2.5 billion messages and updates each day, worldwide. All posted content must comply with the company's standards, which ban many forms of speech that, in the United States, are protected offline. iStockphoto.com hide caption

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Seeds of fear? To most of us, cantaloupe and horn melon look like a healthy breakfast or snack. But the clusters of seeds can evoke anxiety, nervousness and even nausea for some trypophobes. Daniel M. N. Turner/NPR hide caption

itoggle caption Daniel M. N. Turner/NPR

What's up, doc? How would you feel if your doctor shared a picture like this one? Dr. Ryan Greysen hide caption

itoggle caption Dr. Ryan Greysen

Customer review websites like Yelp have exploded in the last few years, but are negative reviewers at risk of inciting the litigious wrath of angry business owners? Richard Vogel/AP hide caption

itoggle caption Richard Vogel/AP

Cameron Harris, who has had Type 1 diabetes since he was 8 years old, explains the ins and outs of using glucagon for blood sugar lows. Harris hosts a video podcast series called "In Range" on YouTube. Harwood Podcast Network/YouTube hide caption

itoggle caption Harwood Podcast Network/YouTube

President Obama and GOP presidential nominee Mitt Romney walk away after they greet each other at the end of the third presidential debate in Boca Raton, Fla., on Monday. Saul Loeb/AFP/Getty Images hide caption

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Republican presidential nominee Mitt Romney and President Obama spar over energy policy during the second presidential debate at Hofstra University on Tuesday. Charlie Neibergall/AP hide caption

itoggle caption Charlie Neibergall/AP

Does he need to watch what he likes? Facebook's logo is reflected in the glasses of a student in Manila. Ted Aljibe /AFP/Getty Images hide caption

itoggle caption Ted Aljibe /AFP/Getty Images