#1. Zuckerberg suffers from red-green colorblindness and sees the color blue best, which is why blue dominates Facebook's color scheme.

#2. AOL and Microsoft tried to recruit him when he was in high school after he created Synapse, a program that used artificial intelligence to learn users' music-listening habits.

#3. He wears the same gray Facebook T-shirt almost every day because he's busy and it saves him time in the morning.

#4. Despite Zuckerberg's casual wardrobe, he said he wore a tie every day in 2009 to show that Facebook was serious about growing in the face of the global recession.

#5. He is a vegetarian and once said he will only eat meat if he has killed the animal himself. But among his "likes" on his Facebook page are McDonald's and In-N-Out Burger.

#6. He has amassed 220,000 Twitter followers despite the fact that he's only tweeted 19 times in four years, and not once in 15 months.

#7. In October 2010, Zuckerberg took a bunch of Facebook staffers to a public theater to see "The Social Network," the movie about the founding of Facebook. In public comments afterward, he criticized the film's portrayal of him as someone who invented Facebook to gain social status.

#8. He owns a Hungarian sheepdog named Beast, who has a Facebook page with 1.5 million fans.

#9. He took some heat last year for giving his wife, Priscilla Chan, a ruby wedding ring that jewelers valued at about $25,000 even though he was worth about $19 billion at the time.

#10. If you type @ [ 4 : 0 ] in a Facebook comment window and hit enter, his name will appear. (without spaces)