since 1977 (earliest usage recorded on this site was 1979)
Applesoft BASIC was a dialect of BASIC supplied on the Apple II computer, superseding Integer BASIC. Applesoft BASIC was supplied by Microsoft and its name is derived from the names of both Apple and Microsoft.
Applesoft was similar to (and indeed had a common code base with) BASIC implementations on other 6502-based computers, such as Commodore BASIC: it used line numbers, and spaces were not necessary in lines. While Applesoft was slower than Integer BASIC, it had many features that the older BASIC lacked including
atomic strings, string arrays, multidimensional arrays, float point variables, high-resolution graphics and user defined functions.