The microwave oven is an invention that arrived almost entirely by accident. Its inventor, Percy Spencer(1894-1970), was an electronics whizz, working on designing radar equipment. He paused next to a "MAgnetron", One of the power components of the machinery, and was amazed to discover that the chocolate bar in his pocket had melted.
Understandably curious, he tried placing other objects near the magnetron. Some unpopped popcorn popped successfully(With Spencer standing further away, so as not to start cooking himself), and the next morning an egg was cooked, demonstrating for the first time that eggs in their shells explode if cooked in the microwave.
Spencer realized the potential of his discovery and set about designing a more efficient food-cooking device. He filed for a patent in 1945, and by late 1946 a prototype device was being tested in a Boston Massachusetts, restaurant, and soon commercial models become available.
These early models were not received well by consumers, possibly because they were over 6 feet tall, cost $5,000 and required special plumbing to cool the magnetron apparatus. Gradually, however, units become safe and reliable enough to be used by the average consumer. By 1975, microwave sales were exceeding those of gas cookers.
The microwave oven does have its shortcomings, however, Meat does not brown on the outside, and the quick cooking time means that food can end up cooked unevenly. Despite these issues, many people regard their microwave as indispensable.