??? “什么是PC？”——雖然這個問題早在iPad問世之前就已經讓分析人士和業內觀察人士困擾多時，但iPad的問世使他們的困擾陡然加深。這個問題并不是簡簡單單就能回答得了的。從某種程度上講，討論它只是浪費口舌，但是要想分析市場行情和公司業績，這個問題又非同小可。

??? 多年來，平板電腦和智能手機一直在擠占PC的銷售市場。這是因為，對于很多人來說，這些新潮而精巧的小機器已經具備他們需要的所有PC（包括筆記本電腦）功能，比如收發郵件、瀏覽網頁、觀看視頻。但是總體上講，它們有些功能還無法與強大的PC相匹敵，比如視頻剪輯、發燒游戲和編程。很多消費者依然想要、或者需要一臺筆記本或臺式機。

??? 把智能手機定義為“PC”乍聽之下或許有些愚蠢。但是很多潛在的PC買家之所以沒有買PC，而是買了智能手機，就是因為他們需要計算設備實現的所有功能，智能手機都已經具備。至于平板電腦，那就更不用說了——而且它還會越來越受歡迎，因為平板電腦同PC的差異一直在縮小（甚至手機也是如此）。用不了多久，我們當中就會有很多人出門帶著PC的替代品當平板電腦使，回到家后就把它插上電源、接上鍵盤，這樣它就變成了一臺功能齊全的PC。

??? 平板電腦與PC的界限之所以一天天變得模糊，硬件和軟件制造商或許也起到了推波助瀾的作用。微軟（Microsoft）新推出的Windows 8操作系統既可以安裝在傳統的筆記本PC上，也可以安裝在與手勢觸控兼容的平板界面上。蘋果（Apple）的Mac OS操作系統也融入了iOS的一些特性，而iOS是讓數以百萬計的iPad、iPod和iPhone發揮強大功能的操作系統。不過，目前蘋果公司尚未推出任何可觸屏的筆記本或臺式機。硬件制造商在競爭對手的圍追堵截下則紛紛借鑒平板電腦和筆記本，采用觸屏科技和超薄封裝。這些所謂的翻轉本，比如聯想（Lenovo）的Ideapad Yoga，既可以做筆記本，也可以當平板電腦，因為它們的屏幕可以360度翻轉。

????現在，人們對PC的概念已是一頭霧水。想想市場研究公司和證券分析師是怎么衡量計算機市場行情的吧。去年，市場研究公司Canalys宣布，蘋果已成為全球最大的PC制造商，但這只是把平板電腦（也就是它所說的“pad”）算進PC中的結果。Canalys表示，“Pad”的銷量占所有PC銷量的四分之一左右。

??? 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.