Which Czech products are most popular around the world? Not cars, not shoes, not turbines, not even locomotives. Computer users know that one of the hottest products is the antivirus program Avast!, created by the Prague company AVAST Software. At the moment, the program protects over 130 million users around the world. Despite the global economic crisis, the company, owned by Pavel Baudiš and Eduard Kučera, keeps thriving. The company's sales have increased to 690 million CZK in the past three quarters and 40 new employees have recently joined the firm.

Baudiš and Kučera met in the 1980s, at Prague's Výzkumný ústav matematických strojů (Research Institute for Mathematical Machines). Computers were still in their infancy at that time and the first virus didn't appear until 1988. One of their colleagues brought it back from a business trip as a souvenir, saved on a floppy disk -- a data storage medium that's now obsolete.

A year later they began dedicating their time to viruses, establishing a company they initially called ALWIL Software. A computer expert was such a rare commodity back then that they were soon inundated with work, mostly from local banks and other businesses. With the turn of the century, the situation changed significantly, however, as larger local firms were bought up by multinationals uninterested in doing business with an obscure Czech firm. "At that time it looked like we would have to close down our business," says Baudiš, and they probably would if ALWIL's programmers hadn't made one last push for survival.

They had no funds for marketing and were literally unknown abroad. So they decided to provide the Avast! antivirus program free of charge to non-commercial computer users across the globe. It wasn't an original strategy but their program had secured a network of loyal users who translated the program's instruction manual into several different languages.

As soon as Avast! made it into households, its success was assured. This was the way to approach wealthy business clients who were willing to pay for their computer protection. Those who tested the program at home had begun to recommend it to their friends and today Avast! (a nautical term meaning "Stop!") is protecting every fifth computer in the world.

And the world has come to Avast!'s aid too. There are around 30 foreigners working for the company at its base near Prague’s Budějovická metro station -- mainly from Europe and North America but also from China and Japan. A year ago, Avast!'s management decided the firm needed an executive director, and selected American Vince Steckler, who moved to Prague from Singapore. It was Steckler who came up with the idea of renaming the company AVAST Software, making it easier for the program's users to remember the company name.

The first virus Pavel Baudiš encountered, 20 years ago, had one goal -- it wanted to multiply. But, unlike the destructive and aggressive viruses that appeared in the mid-1990s, it wasn't malicious. Among the newer viruses, one called Michelangelo gained notoriety. "It formatted the disc and whoever switched on their computer lost all their content," says Baudiš.

It was largely young enthusiasts who were responsible for computer viruses. As well as earning themselves 15 minutes of fame within their own community, they were fascinated by the idea of being able to cause a worldwide epidemic. "Today, it is professionals who create malware and they are trying to be less conspicuous," says Baudiš. Their goal is to steal data (and money from bank accounts) and/or hijack a computer to send spam.

The aim of an antivirus program is to incorporate protection against new viruses as quickly as possible. "We get samples [of viruses] from our users," Baudiš explains. "As soon as they find a suspicious file, they send it to us." Antivirus companies cooperate with each other by exchanging these samples. Only in this way it is possible to analyze the virus, prepare adequate protection and distribute it to users as quickly as possible.

What future plans do Avast!'s successful programmers have? "Our goal isn't to protect every computer in the world," says Kučera. "That would bring us troubles with anti-monopoly authorities. But one third of the world would be enough."

"Or possibly half the world," he adds with a laugh.