平板电脑与PC的界限之所以一天天变得模糊，硬件和软件制造商或许也起到了推波助澜的作用。微软（Microsoft）新推出的Windows 8操作系统既可以安装在传统的笔记本PC上，也可以安装在与手势触控兼容的平板界面上。苹果（Apple）的Mac OS操作系统也融入了iOS的一些特性，而iOS是让数以百万计的iPad、iPod和iPhone发挥强大功能的操作系统。不过，目前苹果公司尚未推出任何可触屏的笔记本或台式机。硬件制造商在竞争对手的围追堵截下则纷纷借鉴平板电脑和笔记本，采用触屏科技和超薄封装。这些所谓的翻转本，比如联想（Lenovo）的Ideapad Yoga，既可以做笔记本，也可以当平板电脑，因为它们的屏幕可以360度翻转。
The question "What is a PC?" has been bemusing analysts and industry observers since long before the introduction of the iPad -- but especially since. The answer is not so simple. In some ways, it's a question of mere rhetoric. But when it comes to analyzing markets and companies, it becomes a lot more than that.
Tablets and smartphones have been cutting into PC sales for years. That's because for many people, the newer gadgets do everything they had previously counted on PCs -- including laptops -- for: email, Web browsing, watching video. But in general, they don't do everything that powerful PCs can do or not quite as well, such as video editing, hardcore gaming, programming. Many consumers still want or need a laptop or a desktop machine.
It might sound silly at first to define a smartphone as a "PC." But lots of people who otherwise might have purchased a PC have opted instead for a smartphone, since it does everything they in particular need from a computing device. That's even more true of tablets -- and it will be increasingly so as the differences between tablets, even phones, and PCs narrow. Soon enough, many of us will be carrying the equivalent of a PC around with us to use as a tablet when we're mobile, and then plugging it in at home, attaching it to a keyboard, and using it as a fully functional PC.
Hardware and software makers may have helped blur the distinction. Microsoft's (MSFT) new Windows 8 operating system can be operated like a traditional desktop PC or via a tablet-like interface that is compatible with touch and gestures. Apple's (AAPL) Mac OS, meanwhile, has adopted some features of iOS, the operating system powering millions of iPads, iPods, and iPhones, though the company doesn't currently sell any touchscreen enabled desktops or laptops. And beleaguered hardware manufacturers have adopted touchscreen technology and ultrathin packages that draw from both tablets and laptops. These so-called convertible laptops, like Lenovo's Ideapad Yoga, double as both because their screens can be flipped back and forth.
For the moment, the PC is confused. Consider how market researchers and stock analysts often measure the computer market. Last year, the research firm Canalys declared that Apple had become the world's largest maker of PCs. But that was only because the firm included tablets (which it called "pads") in its findings. "Pads," Canalys said, made up about a quarter of all sales of PCs.