History buffs still wax poetic about the brutal patent battles a century ago between the Wright brothers and Glenn Curtis, another aviation pioneer. The current smart-phone patent war does not quite have the same romance, but it could be as important. Hardly a week passes without a new case. Motorola sued Apple this month, having itself been sued by Microsoft a few days earlier. Since 2006 the number of mobile-phone-related patent complaints has increased by 20% annually, according to Lex Machina, a firm that keeps a database of intellectual-property spats in America. Most suits were filed by patent owners who hail from another industry, such as Kodak (a firm from a bygone era that now makes printers), or by patent trolls (firms that buy patents not in order to make products, but to sue others for allegedly infringing them). But in recent months the makers of handsets and related software themselves have become much more litigious, reports Joshua Walker, the boss of Lex Machina. This orgy for lawyers is partly a result of the explosion of the market for smart-phones. IDC, a market-research firm, expects that 270m smart phones will be sold this year: 55% more than in 2009. "It has become worthwhile to defend one’s intellectual property," says Richard Windsor of Nomura, an investment bank. Yet there is more than this going on. Smart phones are not just another type of handset, but fully-fledged computers, which come loaded with software and double as digital cameras and portable entertainment centers. They combine technologies from different industries, most of them patented. Given such complexity, sorting out who owns what requires time and a phalanx of lawyers. The convergence of different industries has also led to a culture clash. When it comes to intellectual property, mobile-phone firms have mostly operated like a club. They jointly develop new technical standards: for example, for a new generation of wireless networks. They then license or swap the patents "essential" to this standard under "fair and reasonable" conditions. Not being used to such a collectivist set-up, Apple refused to pay up, which triggered the first big legal skirmish over smart-phones. A year ago Nokia lobbed a lawsuit at Apple, alleging that its American rival’s phone infringes on a number of its "essential patents". A couple of months later, Apple returned the favour, alleging that Nokia had copied some phone features. Since then both sides have upped the ante by filing additional complaints. Lending ferocity to this legal firefight is the fact that competition in the smart phone market is not merely about individual products, but entire platforms and operating systems. These are the infrastructures that allow other firms to develop applications, or "apps", for these devices. Should any one firm gain an important lead, it might dominate the industry for decades—just as Microsoft has dominated the market for personal-computer (PC) software. Yet there is a difference between the smart-phone war and the earlier one over PCs. There is a new type of player: firms with opera-source platforms. Google, for instance, which makes its money from advertisements, does not charge for Android (its operating system for smart-phones) and lets others modify the software. This makes life hard for vendors of proprietary platforms, such as Apple and Microsoft. Some expect Apple and Microsoft t0 sue Google. Yet this is unlikely, because the online giant will be hard to pin down. Google does not earn any money with Android, which makes it difficult to calculate any potential damage awards and patent royalties. The frenzy of smart-phone litigation could last for years. Litigation may also make smart-phones dearer. Mr. White of Bristol York estimates that device makers already have to pay royalties for 200—300 patents for a typical smart-phone. Patent costs are 15,20-of its selling price, or about half of what the hardware components cost. "If 50 people [each] want 2% of a device’s value, we have a problem," says Josh Lerner, a professor at Harvard Business School. Finally, there is a danger that the current intensity of litigation will become normal. Pessimists predict an everlasting patent war, much as the wider information-technology industry seems permanently embroiled in antitrust action. The Wright brothers’ legal skirmishes were put to rest only by the outbreak of the first World war. With luck, thee smart-phone patent: battles will end more quietly. Microsoft may harbor a grudge against Google because

A. the latter’s free platform impairs the benefit of the former.
B. the two companies compete for similar operating systems.
C. the latter is ambitious and eager to develop new applications.
D. the latter poses a threat to the monopoly of Windows system.