XML stands for "extensible markup language" -- extensible because developers can add to it to suit the needs of particular applications. But what makes it really valuable is the fact that it's a language, much like HTML. Unlike some data formats, XML files aren't just streams of incomprehensible numbers. XML is designed to be read by humans as well as machines. A developer who "speaks XML" can look at a document written in an unfamiliar XML dialect and still understand what it's trying to say.
This powerful combination of features makes XML incredibly useful for all kinds of applications. But perhaps its biggest coup was Microsoft's decision to switch to XML-based file formats for Office 2007. As it turns out, you actually may have XML documents sitting on your desktop right now, without realizing it.
Isn't it strange? Your pockets stay the same size, yet you can carry more and more in them every year.
In 1956, IBM's first hard drives used disks that were 2 feet wide. It's hard to believe that today's microscale drives use essentially the same technology. Incremental advances, such as the discovery of giant magnetoresistance and the invention of perpendicular recording heads have produced staggering results. Between 1990 and 2005, magnetic hard drives increased their storage capacity a thousandfold, putting even Moore's Law to shame.
But even with those astounding improvements, hard drives hit a wall when it came to portable devices. They were still too big and too fragile for many gadgets. Enter solid-state drives based on nonvolatile RAM. The technology has been used for storage since the 1970s, but it remained phenomenally expensive until manufacturing processes caught up with the demand. Now it is everywhere: in MP3 players like the newest Creative Zen, and in digital cameras, cell phones, and even some laptops.
Manufacturers aren't sitting still; cutting-edge technologies such as "racetrack memory" could lead to solid-state storage that is smaller, faster, and more reliable than ever.
Lithium ion batteries
When we were kids, our toys came "batteries not included." With our grown-up, high-tech toys, on the other hand, the battery is often one of the most important features. As essential as mobility has become to how we use technology, it simply wouldn't be possible if our choices were still limited to D, C, and AA.