GW-BASIC is a family of BASIC programming languages developed by Microsoft initially in 1981. Microsoft modified their BASIC program to fit the needs of various companies like IBM, Tandy, and Compaq who would include their version of BASIC with the computers they sold. Each version used a similar primitive interface and command set, but they also had unique functionality to work with their different hardware. These versions initially went under a host of different names like Cassette BASIC, Diskette BASIC, Advanced BASIC, and PCjr Cartridge BASIC, but, by the mid-1980s, Microsoft began marketing them all under the name, GW-BASIC. MS-DOS versions 3 and 4 included GW-BASIC, but, by the release of MS-DOS 5 in 1991, Microsoft began distributing the more impressive QuickBASIC.
For a short while in the late 1980s and early 1990s, before my family bought our first computer, I used GW-BASIC on my cousin's Tandy 1000. The very first computer program I had ever written was in GW-BASIC.
I didn't know it at the time, but the Tandy 1000 version of GW-BASIC included special commands to access the machine's 3-voice audio chip. I didn't learn about this until decades later, and I was a bit bummed because my earliest programs still used the terrible PC speaker.