The microwave was invented by Dr. Percy LeBaron Spencer.. The technology behind the microwave was discovered by accident when Spencer noticed that his candy bar melted while working on a radar-related project. He made this discovery, shortly after World War II, in 1946.
When the discovery of the possibility of using a microwave oven to heat food was discovered, units were produced for commercial applications. While they did not have instant success, new iterations of the product saw household units produced for sale. It is estimated that the microwave oven became more popular than typical gas ranges, on a yearly sales basis, during the mid 1970s.