What sets the MacBook Air apart from other clunky laptops on the market is its size -- it's less than an inch thick and weighs fewer than 3 pounds. That means you can toss it in a backpack, messenger bag or average-sized purse and barely know it's there. When it was first introduced in 2008, the thickness of the computer, when closed, varied between .76 inches at its thickest point and .16 inches at its thinnest [source: Apple]. But if you think that's small, consider the fact that over the years the computer has gotten even thinner: The 2011 models were between .68 and .11 inches thick [source: Apple].
At just under 3 pounds, the Air is Apple's lightest laptop yet -- a full 2 pounds lighter than its predecessor, the MacBook. It has an aluminum body, which gives it that sleek, industrial look. But the exterior design is also practical, because the aluminum shell is more durable and resistant to scratches than a plastic body. So even though it's thin and looks a little flimsy, the body is surprisingly strong [source: Snell].
In 2008 you could only buy your MacBook Air in one size: 13 inches. But in 2010 Apple introduced the slightly smaller 11-inch model. The 11-inch Air is the same thickness as the 13-inch model, but smaller in all other dimensions, and it weighs and costs less than the 13-inch model.
The MacBook Air still boasts a full-sized keyboard and screen, keeping it functional and practical for everyday use [source: Apple]. It features a 1280 x 800 resolution backlit LED screen, making everything -- from movies to games to Web sites -- appear sharp and bright [source: Cheng].
One feature that's both fun and practical is that the Air has an ambient light sensor to detect the brightness of the environment around you, then brightens or dims the screen and backlighting on the keyboard accordingly. So if you're computing in the dark, the screen will dim so the light isn't as harsh on your eyes, and if you're outside in the sun it will brighten to make everything on screen easier to see [source: Snell].
Other characteristic design features you'll find on the MacBook Air include a smooth and sensitive trackpad mouse, a built-in camera, a magnetic lid and an impressive seven hours of battery life.