To reduce the computer’s size and weight, Apple omitted certain features long standard on laptops. It is Apple’s first notebook since the PowerBook 2400c without a built-in removable media drive. Users may purchase an external USB SuperDrive, or use bundled Remote Disc software to access the optical drive of another computer. It is the first subcompact laptop offered by Apple since the full-featured 12″ PowerBook G4 was discontinued in 2006. Similarly to the PowerBook Duo series which preceded it, it lacks many features of the larger MacBooks, including a security slot and an Ethernet port, (although a USB-to-Ethernet adapter may be purchased separately). The MacBook Air has a single USB port. Like the entry-level MacBook, the MacBook Air lacks Cardbus and ExpressCard slots, and does not have a FireWire port. The Air is Apple’s first laptop computer to be offered with an optional solid-state hard drive. ArsTechnica found “moderate” performance improvements of the 64 GB solid-state drive over the standard 80 GB hard drive in tests. On October 14, 2008, new models were announced boasting improved capacities of 128 GB (solid-state) and 120 GB (hard drive). The Air comes with 2 GB RAM as standard. The CPU on the original Air was a specially designed Intel Core 2 Duo chip, which reduced the chip’s packaging size by 60 percent. The processor found on the current Air is a low voltage, small form factor Core 2 Duo “Penryn” with 6MB of cache, running on a 1066 MHz bus. The laptop is constructed from an aluminum casing similar to the MacBook and MacBook Pro, however it lacks the visible magnetic latch system. The oversized trackpad offers iPhone-like Multi-Touch gestures, an improvement over previous MacBook trackpads. Among the gestures are pinching, swiping, and rotating. The MacBook Air is pre-loaded with Mac OS X v10.5 and iLife ‘08.

information : wikipedia