The launch of Amazon Web Services in 2006 seemed a puzzling one. Why was Jeff Bezos pushing his online retail company into Web infrastructure services? ("It was a big soul-searching decision," Adam Selipsky, Amazon Web Services Vice President of Product Management and Developer Relations, told Fortune last year.) Seven years later, many companies that wholly or partly operate off AWS -- from Netflix and NASA to Pinterest -- are probably grateful he did. AWS lets many companies to offload costly, time-consuming tasks like setting up servers and managing databases, and focus on their products. Indeed, AWS may be so valuable, RBC Capital Markets managing director Mark Mahaney estimated that it generated $1.5 billion in revenues last year.
Wal-Mart retook the top spot, Berkshire Hathaway made the top five, and Apple grew enormously.