The MacBook is a brand of Macintosh notebook computers by Apple Inc. First introduced in May 2006, it replaced the iBook and 12" PowerBook series of notebooks as a part of the Apple Intel transition. Part of the MacBook family, the MacBook is aimed at the consumer and education markets. It is the best-selling Macintosh in history, and according to the sales-research organization NPD Group in October 2008, the mid-range model of the MacBook was the single best-selling laptop of any brand in U.S. retail stores for the preceding five months.
There have been three separate designs of the MacBook: the original model uses a polycarbonate casing that was modelled after the iBook G4. The second type, introduced in October 2008 alongside the 15" MacBook Pro, used a similar unibody aluminum casing to the 15" Pro, and was updated and rebranded as the 13" MacBook Pro at the 2009 Apple Worldwide Developers Conference in June 2009. A third design, introduced in October 2009, replaced the original casing with a unibody polycarbonate shell.