Microsoft

Bill Gates and Paul Allen founded Microsoft in 1975 on a simple, audacious bet: that the value in computing would shift from the machines to the software that ran them. Their break came in 1981, when IBM chose Microsoft to supply the operating system for its new personal computer. By licensing that system, MS-DOS, rather than selling it outright, Microsoft positioned itself to profit from the flood of IBM-compatible machines that followed, and the software rather than the hardware became the profit center of the industry.

Windows carried the company to dominance. Its graphical operating system became the standard that ran the overwhelming majority of the world's personal computers, and its Office suite of word processor, spreadsheet, and presentation software became the tools of the modern workplace. Gates's stated ambition — a computer on every desk and in every home, running Microsoft software — came remarkably close to reality.

That near-monopoly brought the government down on the company. In a landmark antitrust case at the turn of the century, a federal court found that Microsoft had illegally used its operating-system dominance to crush competition, particularly in the browser wars against Netscape. The company avoided being broken up but emerged chastened, its aura of invincibility cracked even as its wealth made Gates the richest man in the world and funded one of history's largest philanthropic foundations.

Microsoft stumbled in the early mobile and internet era before reinventing itself around cloud computing, whose Azure platform restored it to the front rank of technology companies. From the personal-computer revolution to the cloud and, lately, artificial intelligence, its history maps the shifting center of gravity of the software industry it did so much to create.