Facebook is blue because founder Mark Zuckerberg is red-green colorblind, which means that the best color he can see is blue!
Mark Elliot Zuckerberg (born May 14, 1984) is an American computer programmer and internet entrepreneur. Since 2010, Time magazine has named Zuckerberg among the 100 wealthiest and most influential people in the world as a part of its Person of the Year distinction. In September 2013 his personal wealth was estimated to be US$ 19 billion. In 2011, Zuckerberg ranked first on the list of the "Most Influential Jews in the World" by The Jerusalem Post and has since consistently topped the list every year as of 2013.
Mark Zukerberg only tweeted 19 times in four years.
Mark said he is vegetarian but eat only meat if he killed a animal by itself.
He gifted his wife wedding ruby ring which only cost 25,000 $.
Tag id of mark on Facebook is @[4:0].