The MacBook is a line of Mac laptops sold by Apple Inc. between May 2006 and February 2012. It replaced the iBook series of notebooks as a part of Apple's transition from PowerPC to Intel processors. Positioned as the low end of the MacBook family, below the premium ultra-portable MacBook Air and the performance-oriented MacBook Pro, the MacBook was aimed at the consumer and education markets. It became the best-selling Mac in Apple's history. For five months in 2008, it was the best-selling laptop of any brand in US retail stores. There have been three separate designs of the original MacBook. The original design used a combination of polycarbonate and fiberglass casing which was modeled after the iBook G4. The second design, introduced in October 2008 alongside the 15-inch MacBook Pro, shared the latter's unibody aluminium casing, but lacked a FireWire port. A third design, introduced in late 2009, retained a similar unibody construction but changed back to white polycarbonate. On July 20, 2011, the MacBook was discontinued for consumer purchase as it had been effectively superseded by the MacBook Air which had a lower entry price. Apple continued to sell the MacBook to educational institutions until February 2012. A new line of computers by the same name was released in 2015, serving the same purpose as an entry-level laptop. Polycarbonate (2006–2008) The original MacBook, available in black or white colors, was released on May 16, 2006, and used the Intel Core Duo processor and 945GM chipset, with Intel's GMA 950 integrated graphics on a 667 MHz front side bus. Later revisions of the MacBook moved to the Core 2 Duo processor and the GM965 chipset, with Intel's GMA X3100 integrated graphics on an 800 MHz system bus. Sales of the black polycarbonate MacBook ceased in October 2008, after the introduction of the aluminum MacBook, however the white model continued to be sold until the introduction of the redesigned unibody polycarbonate MacBook. While thinner than its predecessor – the iBook G4 – the MacBook is wider than the 12-inch model due to its widescreen display. In addition, the MacBook was one of the first (the first being the MacBook Pro) to adopt Apple's MagSafe power connector and it replaced the iBook's mini-VGA display port with a mini-DVI display port. The iBook's discrete graphics chip was initially replaced by an integrated Intel GMA solution, though the latest revisions of the MacBook