It was 10 years ago this month that a 21-year-old Linus Torvalds sent an email to the open-source software community saying an experimental version of the Linux kernel, the core technology that would end up embodied in Linux operating systems, was up and running. "I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones," Torvalds wrote in an email to a discussion group that focused on the Unix variant Minix. "This has been brewing since April, and is starting to get ready." Torvalds posted version 0.01 of the kernel the following month. While Linux lacked some of the features and big-name backing of other operating systems, it had a giant appeal--those who adopted it could tailor it as they saw fit. Since that note, Linux has become a worldwide phenomenon. By last year, less than a decade after its inception, Linux had 27 percent of the server market, according to researcher IDC. That compares to 41 percent of the market held by Microsoft's Windows. Just as important, Linux popularised the concept of open-source software, where developers freely exchange intellectual property. Advocates say open-source concepts will revolutionise software. By contrast, Microsoft has likened open licenses to cancer and called them un-American. Robert Young, who would go on to launch Linux leader Red Hat, said it was 1993 when he first noticed the excitement that Linux was generating, particularly among the system administrators who tailored off-the-shelf software to do the particular work they needed to do. "For the first time, they had control over the technology they were using," he said. At the time, almost nobody was helping large companies move to Linux. Young, who also points out that he is Canadian when the un-American charge comes up, sensed an opportunity. Less than two years later, in January 1995, Red Hat was born. Of course, it took another four years for big-name computer makers and the investment community to take notice. But when they jumped in, they went in headfirst. Despite uncertainties about how companies would generate money for an operating system that was freely distributed, shares of Linux companies soared, most notably the record-setting December 1999 initial public offering of VA Linux, in which shares soared 698 percent to close at $239.25 on their first day of trading. But as enthusiasm for tech stocks waned, Wall Street lost its infatuation with Linux, sending shares plummeting. VA Linux now trades around $2 a share, and a number of Linux firms have been slashing jobs and eyeing consolidation. Today, the culture clash between the mainstream PC business and the open-source community is as big as ever. While Microsoft and Intel celebrated the 20th anniversary of the IBM PC with a giant party in San Jose, members of the Linux community plan more subdued celebrations in various locales, including a gathering later this month at a Sunnyvale, California, park. The contrasts in ceremonies highlight the different approaches of Microsoft and the Linux community. The Wintel bash was an open bar followed by a formal dinner and panel discussion. The Linux event is a BYOB barbecue. Still, many who have spent a long time partying with Microsoft and Intel are also sharing in the rewards of open source. Although some criticise IBM for failing to capitalise on its own PC standard, the company is working hard not to miss out on the opportunities Linux presents. The company has said it will spend $1bn (£700m) this year on its Linux-related activities. Daniel Frye, head of IBM's Linux Technology Centre, said it was three years ago this month that IBM decided at the corporate level to consider using Linux. At the time, there were 7 million people using the software; it already had a massive development community and was popular with market segments where IBM wanted to expand, such as e-commerce. "Just a brief glance said we've got to look at it closely," Frye said. Since the initial decision to pursue Linux, Big Blue has continued to step up its commitment to the operating system, adding Linux support for all its key hardware and software lines. IBM also offers the same service contracts, in terms of guaranteed response times and reliability, as it does with other operating systems. Linux has come a long way to reach the point where companies such as IBM, Compaq Computer, Hewlett-Packard and Intel are taking it seriously. The operating system has grown up, starting with version 1.0 released in 1994 through version 2.4 released in January 2001, adding support for new and faster chips and ever-increasing amounts of memory. More than its features, it is the collaborative nature of Linux development that has made the software a success, Young said, maintaining that the Linux movement is on the "correct side of history. "History is about moving from feudal systems with top-down control into collaborative systems," Young said. "The proprietary (OS) model looks more like the feudal model than the free-market system." Young said having computers with a proprietary operating system would be akin to Ford shipping cars that had a locked hood that only Ford could open. Already, Linux has moved far beyond its roots in large corporate computer systems, invading handheld computers and other non-computer devices. IBM has demonstrated a Linux-based wristwatch, although the market for such devices is not entirely clear. "Nobody is selling a Linux watch, but (look) for it in a year," Frye said. The operating system is also moving further into the realm of high-end computing, Frye said. "Customers are buying brand-new mainframes just to run Linux," Frye said, adding that such purchases would have been unthinkable just two years ago. Still, the operating system has challenges ahead. Frye said that while Linux has always been reliable, meaning it fails infrequently, it needs to be more available, meaning problems are handled swiftly when they do crop up. And although Linux has become popular in large clusters of computers, such as the 1,000-system Linux cluster purchased by Royal Dutch Shell, Frye said he looks for improvements that will allow a single image of the operating system to effectively utilise multiple processors, a feature known in the computing world as symmetric multi-processing. There have also been issues of perception as Linux has entered new markets. Frye recalled debates inside IBM of whether it could really be a part of an open-source community and whether its blue-chip client base would buy an operating system that no one company was responsible for. "We have," Frye said. "They did." Young is convinced the Linux movement is only in its infancy. "Ten years from now people are going to be writing the same sorts of stories (as the IBM PC anniversary), asking 'Did you have any idea how big it was going to be?'" Young said. Still, Young said he could not predict where Linux would take off next, whether in a Web server, a next-generation cell phone or some product that hasn't been thought up yet. See the Linux Lounge for the latest GNU/Linux and open source headlines. See the Operating Systems News Section for the latest headlines on Linux, Windows and other operating systems. See the Software News Section for full coverage. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the Linux lounge forum Let the editors know what you think in the Mailroom. And read other letters.