The MacBook Air is a line of Macintosh ultraportable notebook computers from Apple Inc. The Air was designed to balance both performance and portability, consisting of a full-sized keyboard design, a machined casing made of aluminium, and a very light and thin structure. The MacBook Air is available in two sizes, with the length of the diagonal display determining the model size: 13.3-inch and 11.6-inch (or 33.78 cm and 29.46 cm, respectively). A range of model choices with different specifications are produced by Apple, and as of 2014, all Air models use solid-state drive (SSD) storage and Intel Core i5 or i7 central processing units (CPUs).^[2]

In the Macintosh product line, the MacBook Air sits below the thicker and higher-performance MacBook Pro. The MacBook Air was originally released as a premium ultraportable which was positioned above the white MacBook.^[3] Since then the MacBook Air has become Apple's entry-level laptop due to the discontinuation of the white MacBook in 2011, as well as lowered prices on subsequent iterations of the MacBook Air.^[4] In recent years the MacBook Air has become the best-selling Macintosh computer and the best-selling ultraportable^[5][6] being credited with revolutionizing lightweight yet powerful laptops known as Ultrabooks.^[7]