It's also a device that Apple has put both its technological and marketing weight behind since day one. "iPad is our most advanced technology in a magical and revolutionary device at an unbelievable price," Jobs said when introducing it on January 27th, 2010. "We believe that iPad is the perfect expression of the future of personal computing," current CEO Tim Cook said at a 2016 event unveiling the 9.7-inch iPad Pro. Hell, Jobs even described something that sounded like the iPad all the way back in 1983: "What we want to do is we want to put an incredibly great computer in a book that you can carry around with you that you can learn how to use in 20 minutes," he said at the 1983 International Design Conference in Aspen.

Apple's bullishness on the iPad has continued unabated, even as sales dropped off after peaking at 26 million during the 2013 holiday shopping season. The years since have seen Apple experiment with a variety of screen sizes, features and price points in an effort to jump-start interest. But while sales eventually leveled off, the iPad generates the least revenue of any Apple product line. Over the past five years, Apple's services and wearables / accessories divisions have exploded, while the iPad has basically stayed flat. But the $4.66 billion in iPad revenue Apple earned last quarter -- as well as Apple's own insistence on the iPad as the future of computing -- is enough to suggest that the device is here to stay.

From the jump, Apple used the iPad to introduce important new technology, something that has continued over the last decade. It's easy to forget now, but the first Apple-designed, A-series processor was the A4, which was used in the first iPad and soon brought over to the iPhone 4. Of course, it turned out that the single-core A4 wasn't quite powerful enough, as Apple stopped providing software updates to the original after less than three years -- an uncommonly short lifespan for an iOS device. (As someone who owned a first-generation iPad, I can attest that the iOS 5 upgrade in the fall of 2011 nearly brought the tablet to its knees.)

Fortunately, Apple started developing higher-performance chips made specifically for the iPad, starting with the A5X in 2012. In more recent years, the A12X processor in the latest iPad Pro compares favorably with some of Intel's more powerful consumer CPUs, at least in some tests. It's not easy to do direct comparisons, but it's undeniable that Apple has done some serious innovating to make such powerful processors run without fans in a small enclosure while still maintaining strong battery life.

Apple has also made great strides in its iPad display technology over the years. The early 2012 refresh was the first large-screen device to get a Retina-class screen, something customers had been asking for since the iPhone 4 arrived in June 2010. Later that year, Apple brought a display of the same caliber to Mac too, but it worked on the iPad first. A few years later, the 9.7-inch iPad Pro was Apple's first device with the so-called True Tone display. That device included sensors that matched the screen's ambient temperature with that of the light in the room, making the screen more comfortable to read. That tech is now available in nearly all iPads as well as most Macs and iPhones.

Of course, Apple wouldn't be Apple if it didn't take years to introduce some technology many thought was necessary from day one. While the first Microsoft's Surface didn't get everything right, the stylus and keyboard cover were both extremely useful accessories from the very beginning. iPad users, on the other hand, had to use third-party stylus and keyboards, many of which were of questionable quality, until Apple finally released its own alongside the 12.9-inch iPad Pro. And it took a few years before those accessories worked with Apple's lower-priced iPads as well.