When it comes to what we'd call the "modern" businesses of today, there are 4 giant players that dwarf everyone else: Apple, Amazon, Google and Facebook. Although these "Cyber Fab 4" do most of their business online (Apple is the exception that we'll cover in a bit), they threaten the existence of a group of giant traditional businesses in a wide range of industries, as outlined in the infographic below.
By the way, which of the 4 has a different business model from the others? It's Apple, which basically uses its software to get you to buy their high-margin hardware. It's hard to say that that's a better business strategy, but it sure is working well for them as some analysts predict their stock will go to $500 soon.