The Apple II series (trademarked with square brackets as "Apple ][") is a set of 8-bit home computers, one of the first highly successful mass-produced microcomputer products, designed primarily by Steve Wozniak, manufactured by Apple Computer (now Apple Inc.) 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 (and allowed several related companies to start). Throughout the years, a number of models were sold, with the most popular model remaining relatively little changed into the 1990s. It was first sold on June 10, 1977. By the end of production in 1993, somewhere between five and six million Apple II series computers (including about 1.25 million Apple IIGS models) had been produced.
The Apple II became one of several recognizable and successful computers during the 1980s and early 1990s, although this was mainly limited to the USA. It was aggressively marketed through volume discounts and manufacturing arrangements to educational institutions which made it the first computer in widespread use in American secondary schools. The effort to develop educational and business software for the Apple II, including the 1979 release of the popular VisiCalc spreadsheet, made the computer especially popular with business users and families.