The Apple II series is a family of home computers, one of the first highly successful mass-produced microcomputer products, designed primarily by Steve Wozniak, manufactured by Apple Computer and introduced in 1977 with the original Apple II. In terms of ease of use, features and expandability the Apple II was a major technological advancement over its predecessor, the Apple I, a limited-production bare circuit board computer for electronics hobbyists that pioneered many features that made the Apple II a commercial success. Introduced at the West Coast Computer Faire on April 16, 1977, the Apple II was among the first successful personal computers; it launched the Apple company into a successful business. Throughout the years, a number of models were sold, with the most popular model remaining relatively little changed into the 1990s. While primarily an 8-bit computer, by mid-run a 16-bit model was introduced.