A Microsoft executive calls the GPL a "viral" license, because it "spreads to everything it touches". But Microsoft understands the real reason they should fear the GPL. The GPL is impervious to them. Microsoft is in the business of monopoly. Their primary target audience is everyone, for everything. They have attempted to overthrow the video gaming industry and have done well, but not well enough. They've had reasonable success taking control of the Internet. Here they remain a double digit player in the server industry and have launched a new development platform with which to entrench intellectual expense deeper into their system platform. Their web browsing product dominates the world even though it is full of security flaws and renders HTML improperly according to the web standards, making it more difficult for competitors to compete without themselves conforming to the idiosyncrasies of the Microsoft way, but also costing developers of web sites thousands of hours in productivity by making the circumvention Internet Explorer's flaws a frustrating art. Yes, it is they that are the virus, for they are trying to swallow all of human industry and sell it. They produce a product, decimate the playing field, then let the product rot, using updates to usher more unsuspecting users into your trap. Internet Explorer has been left in mothballs for years without a line of forward progress, and now it returns to life just as Firefox threatens to finally offer something so superior that people will switch. So is it any wonder that the Gnu Public License wishes to prevent Microsoft from using other people's freely-written to it's own benefit? Without such a license, Microsoft could patch the cracks in their software completely on the backs of others who needed it done, but continue to profit from it grossly. The license simply says, if you make a derivative work of this code, you must be willing to grant others that right as well. It isn't a virus, it's just designed to stop a parasite.