A camera is a gadget that records and stores images. For decades, it was the box camera that ruled the roost. It was cheap and simple, yet produced very good results. These cameras had a single element lens, limited aperture control, and a leaf shutter that had single speed. Box cameras were also called viewfinder cameras.
Folding roll cameras also became popular which in essence were types of box cameras only. In these cameras, lens was contained in a movable bellows that could move forward and backward, which allowed the lens to change focus. These cameras were foldable and thus easy to take on vacations
Rangefinder cameras do not use a lens to view the object. They rather have a separate viewing system to aim and view. In these cameras 
there are two images in the viewfinder. One that is yellowish is only a part of the view that the person gets. These cameras are very accurate and lightweight. They are ideal for taking pictures in low light.
Twin lens reflex cameras are fitted with two lenses, one atop another. The lower lens focuses its image on the film, while taken by the upper lens is reflected at right angles using a mirror and brought to focus on a horizontal screen.
Single lens reflex cameras or the SLR does viewing and photographing with a single lens. Light going through the lens is directed through a mirror on a horizontal glass.
Instant cameras produce a finished photo within minutes. Also known as Polaroid cameras, the film after exposure is passed between two rollers which causes rupture of a chemical pod that spreads developing agent on the film and the print comes out.
Disc cameras make use of film that is rolled on a spool or loaded into a cassette. These cameras are very compact and are fitted with a flash and a motor that advances the disc after each exposure.
Point and shoots cameras are viewfinder cameras with special abilities of focus. These cameras are perfect for taking on vacations. These cameras have a wide angle lens and you can get closer to the object to take a close up.