@imhellokitty, Instamatic cameras were made by Kodak, not Polaroid. They came out in the 1960s. Here is a picture of an early model:
http://blog.wired.com/gadgets/766px-Kodak_Instamatic_100%201.jpg
The one shown in the picture above had a pop-up flash. Later models used flash cubes, which were quite an innovation for the time: you could take 4 flash pictures in rapid succession.
However, the real innovation from the Instamatic camera was its 126 Kodacolor film cartridge. Prior to the Instamatic, all cameras used roll film. If you weren’t particularly good with your hands, you’d end up ruining a lot of film. With a drop-in cartridge, however, you could simply open the back of the camera, remove the exposed cartridge, and drop in a new one.
Unlike Polaroid cameras, pictures taken with an Instamatic had to be lab-developed, just like roll film. What you got back wouldn’t make you an Ansel Adams, but cameras like this made photography a lot more accessible to ordinary folks.