History will record that Mark Zuckerberg wasn’t the first college student to have the idea of enabling people to set up Web pages and share stuff with their friends. Yesterday, my colleague Silvia Killingsworth wrote about the Winklevoss twins, two Harvard grads who famously accused Zuckerberg of stealing the idea for Facebook while working on their fledgling site Connect U. Before the Winklevii, there were the folks behind MySpace and Friendster. And before them, way back in 1995, there were Todd Krizelman and Stephen Paternot, who launched TheGlobe.com from their dorm rooms at Cornell.

TheGlobe.com allowed people to create their personal space online, upload pictures, and set up what came to be known as blogs. By 1998, it had more than two million members, which was then considered impressive. It also had a business plan: sell advertising. On November 13, 1998, Bear Stearns issued 3.1 million shares in the company at nine dollars each to some of its clients—the lucky ones. When Bear’s traders tried to open the stock for trading, they found it difficult to establish a floor price. As I recalled in my 2002 book, “Dot.Con: The Greatest Story Every Sold” (apologies for the plug):

Whatever price they indicated—$20, $30, $40, $50—was too low. CNBC reported that the first trade might be $70, but even this proved to be a conservative estimate. After a lengthy delay, the first trade crossed the ticker at $87—almost ten times the issue price. Even for an Internet stock, this was unheard of. Within an hour, the price had risen to $97.

TheGlobe.com’s I.P.O. marked the beginning of the dot-com bubble’s epic stage. By the time the bubble burst, in March and April, 2000, hundreds of online firms had issued stock, among them many clunkers like Pets.com, E-Stamp, and etoys.com (not to be confused with a later company that used the same name), but also many online companies that survived and eventually thrived, such as eBay, Amazon.com, and Priceline.com. The bursting of the bubble discredited the term “dot-com,” which was understandable but, in a way, unfortunate, because the term itself had come to be the expression of an attitude that saw in online communication and online commerce boundless possibilities. Facebook’s I.P.O. represents a return to that mindset. It’s the fulfillment of the dreams of the nineties—and a reminder of their potentially fatal attraction.

While the term “dot-com” disappeared, the idea survived. Before very long, it was rebranded as “Web 2.0”—a term popularized by Tim O’Reilly and John Battelle, who from 2004 onwards organized a series of conferences under this banner. Supposedly, what distinguished Web 2.0 from Web 1.0 was user control, and user collaboration, with the network serving as a “platform,” but that wasn’t really a new idea: Krizelman and Paternot had fastened upon it years earlier, as had the founders of GeoCities and other Web-hosting ventures.

What really got Web 2.0 going was the proliferation of broadband connections, the invention of top-notch search engines (Google), and the creation of idiot-proof tools for doing fun stuff online, such as sharing photos and videos, posting blogs, and creating mashups. By February, 2004, when Zuckerberg launched Facebook, the elements were in place for the Web to fulfill the hopes of the late nineties—or some of them, anyway. But if Zuckerberg was in the right place at the right time—nobody should underestimate the role that the “Harvard” brand played in Facebook’s initial growth—he seized the opportunity ruthless and brilliantly. Now, seven years later, he is about to become a billionaire many times over by selling (non-voting) shares in what is, in many ways, the ultimate dot-com.

Back in the late nineties, I used to read a lot of S-1s—official investment prospectuses produced by companies about to issue public shares for the first time. Delving into Facebook’s S-1, which it has amended repeatedly since February, when it put out an initial version, felt like old times. The numbers were different (by an order of magnitude) from those that the original dot-coms used to put out, but the basic story was the same one that had led to all those bad investments and broken dreams: a Web site expanding this fast, with this many eyeballs focussed upon it, has simply got to be worth a lot of money.

Certainly, Facebook’s growth has been astonishing. As of March 31st, some nine hundred million people—about one in eight of all the humans on the planet—used the site at least once a month. More than five hundred million people—about one in thirteen of the global population—used it daily. Every day, Facebook users upload about three hundred million photographs and generate about 3.2 billion “likes” and “comments.” People on Facebook have a hundred and twenty-five billion “friends.” For many of us, Facebook has become a part of daily life. Many use it to keep up with friends; some use it as a news service; I’m in the camp of those who utilize it mainly as a professional tool. (Once I put up this post, I will link to it on my page.)

Compared to the late nineties, there are some basic differences, of course. Unlike many of the original dot-coms, Facebook makes money—quite a lot, in fact. It sells advertising and also charges other firms that use the site to drum up business, such as the gaming company Zynga and the music service Spotify. In 2011, on revenues of $3.7 billion, Facebook generated a billion dollars in profit. In the three months to March 31st, it made another two hundred million dollars.

That’s reassuring, but does it justify a valuation of a hundred billion dollars? That’s what the company will be capitalized at if the underwriters, led by Morgan Stanley—another echo of the late nineties—price its stock at the upper end of the $34-$38 range they indicated on Tuesday. If the stock goes up when trading starts, and it almost certainly will, Facebook will be even more highly valued. While I don’t think Facebook’s stock will enjoy the sort of crazy leap that TheGlobe.com’s took, I wouldn’t be at all surprised to see it close over fifty dollars, which would value Facebook at more than a hundred and twenty-five billion dollars.

For such a figure to make sense, given the risks attached to the technology industry, you have to assume that, within a few years, Facebook will be making not a billion dollars a year in profit but five billion dollars, or ten billion dollars, or even more. Apple, the world’s most valuable company—its market cap passed six hundred billion dollars briefly last month, and is currently hovering at a little more than five hundred billion—generated more than twenty-five billion dollars in profits last year. Microsoft, which is valued at less than half of Apple, made more than twenty-three billion. Google, valued at about two hundred billion, made nearly ten billion.