His landmark invention came after WWII ended. While on vacation, Land’s three year old daughter asked him why she couldn’t see a photo he had taken of her right away. He tried to explain to her they still needed to be developed, but that didn’t comfort her.

So Land went into the lab and created a system of one-step photography using the principle of diffusion transfer to reproduce the image recorded by the camera’s lens directly onto a photosensitive surface—which now functioned as both film and photo.

Polaroid originally manufactured 60 units of The Land Camera. 57 were put up for sale at Boston’s Jordan Marsh department store before the 1948 Christmas holiday. Polaroid marketers incorrectly guessed that the camera and film would remain in stock long enough to manufacture more. They were wrong. All 57 cameras and all of the film sold on the first day.

The story of Polaroid inventor Edwin Land, one of Steve Jobs’ biggest heroes - (37signals)