Mark Zuckerberg, Eduardo Saverin, Andrew McCollum, Dustin Moskovitz, Chris Hughes, Sean Parker, 2004

Facebook is a social network that was launched in 2004. Initially it served as a network for Harvard University students. Eventually Facebook became available, with a few exceptions, to the rest of the world. So unless you are living in Iran or China, you can use Facebook to upload photos, state your status and respond to other people’s posts or simply ‘Like’ them. These four ingredients are the basis of this highly-addictive social platform where you can follow your friends, colleagues, family and other acquaintances. The more the merrier. In theory, you could have 1 billion people be your friend.