Pinhole photography is photography at its most basic. Pinhole cameras can be made from any light-tight container by making a small “pinhole” in it that will serve as the lens. The images are usually very wide angle with infinite depth of field but are also less sharp than with a standard lens… resulting in soft dreamlike images.
I make many of my cameras out of Altoids tins and 35mm film containers. I usually use black and white photo paper as negatives, process them in the darkroom, then scan and post-process in Photoshop.
There is a wealth of information about pinhole photography available online. I recommend starting with Wikipedia if you are interested in learning more about it.