The MacBook Pro (sometimes unofficially abbreviated as MBP) is a line of Macintosh portable computers introduced in January 2006, by Apple Inc. It is the higher-end model of the MacBook family, sitting above the consumer-focused MacBook Air, and is available in 13-inch and 16-inch screen sizes. A 17-inch version was sold from April 2006 to June 2012. The first-generation MacBook Pro used the design of the PowerBook G4, but replaced PowerPC G4 chips with Intel Core processors, added a webcam, and introduced the MagSafe power connector. The 15-inch model was introduced in January 2006; the 17-inch model in April. Later revisions added Core 2 Duo processors and LED-backlit displays. The second-generation model debuted in October 2008 in 13- and 15-inch variants, with a 17-inch variant added in January 2009. Known as the "unibody" model because its case was machined from a single piece of aluminum, it had a thinner flush display, a redesigned trackpad whose entire surface was a single clickable button, and a redesigned keyboard. Updates brought Intel Core i5 and i7 processors and introduced Intel's Thunderbolt technology. The third-generation MacBook Pro was released in 2012: the 15-inch in June, a 13-inch model in October. It was thinner than its predecessor, made solid-state storage standard, and included a high-resolution Retina display. The fourth-generation MacBook Pro was released in October 2016. It uses USB-C for all data ports and power and introduced a shallower "butterfly"-mechanism keyboard. In all current MacBook Pro, the function keys were replaced with a touchscreen strip called the Touch Bar with a Touch ID sensor integrated into the power button, and feature at least four cores. A major revision was released in November 2019 that enlarged the screen to 16 inches by narrowing the bezels and returned to a scissor-mechanism keyboard.