The MacBook is a brand of notebook computers manufactured by Apple Inc. from early 2006 to late 2011. It replaced the iBook series and 12-inch PowerBook series of notebooks as a part of the Apple–Intel transition from PowerPC. Positioned as the low end of the MacBook family, below the premium ultra-portable MacBook Air and the powerful MacBook Pro, the Apple MacBook was aimed at the consumer and education markets. It was 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 US retail stores for the preceding five months.There have been three separate designs of the MacBook: the original model used a combination of polycarbonate and fiberglass casing which was modeled after the iBook G4.The second type, introduced in October 2008 alongside the 15-inch MacBook Pro, used a similar unibody aluminum casing to the 15-inch Pro, but lacked Firewire, as a cost-balance with the more expensive aluminum case. Sales were poor and customers complained of the lack of Firewire.A third design, introduced in January 2009, reverted to the polycarbonate shell and, in response to customer backlash, reverted to Firewire again like all MacBooks prior to the Late 2008 model. In this sense, it was really the first design revisited. A Mid 2009 model also had Firewire, but with the Late 2009 release, Firewire was again dropped by Apple.On July 20, 2011, the MacBook was quietly discontinued for consumer purchase as it had been effectively superseded by the MacBook Air whose starting price was lowered. Apple continued to sell the MacBook to educational institutions until February 2012.