Steve Jobs's resignation as Chief Executive Officer of Apple is the end of an extraordinary era, not just for Apple, but for the global technology industry in general. Mr. Jobs is a historic business figure whose impact was felt far beyond the company's Cupertino, California headquarters, and who was widely emulated at other companies. And now, for the first time since 1997, he won't be CEO.

To be very clear, Mr. Jobs, while seriously ill, is very much alive. People with direct knowledge of the matter say he intends to remain involved in developing major future products and strategy and intends to be an active chairman of the board, even while new CEO Tim Cook runs the company day-to-day. This is not an obituary. But his health is reported to be up and down, and even an active chairman isn't the same as a CEO.

CEOs resign every day, so why is this one so meaningful?

Most people are lucky if they can change the world in one important way, but Mr. Jobs, in multiple stages of his business career, changed global technology and media in multiple ways on multiple occasions. And that changed the way people live.

He did it because he was willing to take big risks on new ideas, and not be satisfied with small innovations fed by market research. He insisted on high quality and had the guts to leave out features others found essential and to kill technologies, like the floppy drive and the removable battery. And he has been a brilliant marketer, personally passionate about his products.

In his first act at Apple, the company he co-founded in 1976, he helped envision and catalyze the personal computer revolution. The Apple II computer he developed with Steve Wozniak wasn't the only mass-market PC released in 1977, but it was the one that had the most enduring impact.

In 1984, he again upended computing by leading the development of the Macintosh, the first commercially successful computer to use a mouse and graphical user interface. It cemented the template for how every computer works today, even though Apple was handily bested in the PC sales wars by archrival Microsoft.

After being forced out of Apple in 1985, it's well known that Mr. Jobs ran an unsuccessful computer firm called NeXT. But he also did a couple of game-changing things during that exile. First, NeXT developed an operating system that later morphed into the excellent Macintosh operating system, called OS X, and also the operating system that drives Apple's mobile devices, called iOS.

Along the way, he purchased Pixar, a small computer animation firm which he turned into one of the world's most successful movie studios, later sold to Disney for $7.4 billion. It changed animation forever.

His latest act began in 1997, when he returned to take over as CEO of Apple as part of that company's purchase of NeXT. What he found was a diminished company, saddled with mediocre products and reputedly only months from bankruptcy.

Fourteen years later, the company is a highly profitable behemoth, the most financially valuable and influential technology company in the world, whose every product is eagerly anticipated, snapped up quickly by consumers, and aped by competitors, even though they are often priced higher than rival devices.

While CEO of the revived Apple, he introduced the dominant digital music player, the iPod, and created the most successful digital media service, iTunes. He introduced the first super-smartphone, the iPhone, and the only truly successful tablet computer, the iPad, which is in the process of replacing the laptop, at least in part. He built the world's largest app store. One almost forgets that he built a phenomenally successful chain of retail stores, too.

Jobs has dramatically changed the mobile phone industry, the music industry, the film and TV industries, the publishing industry and others.

Even while declaring that we are in the 'post-PC era,' Steve Jobs resuscitated his early baby, the Mac. While it may never become the world's biggest selling computer, it is lusted after worldwide, and its sales have outgrown those of the overall PC industry for five years running. The evolution continues with models like the sleek, solid-state MacBook Air, which merge aspects of the tablet and the PC.

Now, rumors are rife that Apple is working on re-inventing another common device: the TV. The secretive company won't say a word about that, but based on Mr. Jobs' track record, nobody should be surprised if it happens.

And that's why the day Steve Jobs resigns as CEO of Apple isn't like the day a typical CEO resigns.