A brief definition of pinhole photography
Pinhole photography could be made with a light tight box that has a pinhole at one end and light sensitive material at the opposite end. You don't need a lens to make a photograph.
The effect is that of an overall softness and endless depth of field. In other words the same degree of softness will be seen on a subject that is close to the camera as well as a subject that is far away. All this in the same photo.
Because the pinhole is so small some exposures may take up to 5 minutes or more. People passing in front of the camera on long exposures may not even be seen in the picture. Sometimes they will have a phantom transparent effect.
Pinhole photos remind me of the impressionist paintings such as the works of Monet, Manet, Pissarro and Van Gogh. The paintings have a softness that you can see in pinhole pictures, whether it's portraits or scenery.
For more details please refer to the world pinhole day website (pinholeday.org) as well as the Stenopist website (lesstenopistes.com).