Facebook is blue because Mark Zuckerberg is colour-blind
The dominant colour of Facebook is blue as the company Co-founder and CEO Mark Zuckerberg has red-green colour blindness. Zuckerberg, who took an online test and realised that he was colour-blind, revealed in an interview, "Blue is the richest colour for me, I can see all of blue." Notably, the social networking site was launched on February 4, 2004.