Simons' BASIC is an extension to BASIC 2.0 for the Commodore 64 home computer. Written by British programmer David Simons in 1983, who was 16 years old at the time, it was distributed by Commodore as a cartridge.
It is widely, but incorrectly, called "Simon's BASIC", because of confusion between the first name "Simon" and the surname "Simons".