Collectively, the MacBook brand is the 'world's top-selling line of premium laptops.' For five months in 2008, it was the best-selling laptop of any brand in US retail stores. Positioned as the low end of the MacBook family, below the premium ultra-portable MacBook Air and the powerful MacBook Pro, the MacBook was aimed at the consumer and education markets. It replaced the iBook series of notebooks as a part of Apple's transition from PowerPC to Intel processors. A new line of computers by the same name was released in 2015, serving the same purpose as an entry-level laptop. The MacBook is a line of Macintosh notebook computers designed, manufactured and sold by Apple Inc.