It is also known as sténopé in French, or simply Camera Obscure, and its technical aspect have been know since 470 BC or probably even before. But the earliest description texts about camera obscure date from this year.
The foundation of any photographic camera is a light proof box, that have a small hole to let a small fraction of light getting in. This small fraction of light will reproduce a image of what is outside and in front the the camera. This is how every camera works.
For this reason pinhole cameras are known for have very small apertures, like the f320 and f233 stop I have on my cameras for example, something around 0.3mm and 0.4mm hole.
With such small aperture to let the light in, pinhole photography is also know for its long exposures photographs. This also means that it doesn't require mechanical shutter. You simply make the exposure by taking the hole cover out and by putting the hole cover on when the exposure time is finish.
Pinhole cameras need such small holes in order to reproduce a recognizable image, otherwise the image will be blurred or the image won't appear at all.
Now, why there are people like me who enjoy or even prefer to photograph with pinhole cameras?
1. Its simple mechanism and tool allow anyone to build their own camera spending almost nothing and requiring very little skill and knowledge. And building your own camera is fun, as well as taking photographs with the camera you built yourself is pleasing. Appreciating the image from a such simple tool that you made yourself is really nice. It is like cooking and eating the food you grow in your own garden.
2. While a lot of photographers, specially hobbyists, enjoy and expect to have cameras with many functions and options to choose in order to take the maximum kind, type and effect of photographs with their cameras in any moment, many others goes on the other direction, finding the simpler it is the better for them. Specially because the more options, effects, image look and a camera can offer, the more such variability and decision making becomes a distraction to photographer from photography itself. Pinhole cameras are straight forwards.
This is the same reason people like Obama or Bill Gates have the clothes in their wardrobe looking all the same. When they wake up in the morning they don't have to spend time and attention to think about what they are going to ware on the day and about their clothes look on the day. Less distraction for their busy life.
Of courser it is nice to have a tool for those who wan't to make all kind of things with it. Like a computer with a operational system that allow to use the machine for work, games, watch films, edit photographs, make the personal finance accountability, etc... But a too dedicated for a more specific work is usually better for those dedicated to such specific work and result. Like the dinosaurs computers on modern planes and space ships that never fail and last long because they have nothing else to process other than a very limited and specific information.
3. The more dedicated the tool, the best for a dedicated result. Like my 6x17 panoramic camera with curved plan and two pinholess that allow me to take a stream wide angle of 141º with no vertical distortion and no distortion on the skyline.
4. The simpler the tool the longer it last. Because with no mechanical but all manual mechanism, there is nothing to get broken and fixed. No worries about using your camera on extreme weather, no worries about camera impact. The only way to break the camera is by smashing it and if its happens, you can easily build an other one.
5. Very light and compact. Since it doesn't use glass lenses you don't need to carry a bag of different lenses with you. Since the camera is just a empty box it is like carrying a empty bag. The down side is in most of cases it will require a tripod that you have to carry with your camera, due to the long exposures aspect, which doesn't mean it has to be a big and heavy tripod depending of the type of photographs you do.
But even if you carry two 5x4" pinhole camera on your bag, or maybe more, you still have a more compact bag than carry a most full frames 35mm digital cameras, and their lenses.
These are some of the main aspects of pinhole cameras. It will be a very joyful and even dedicated tool for some photographers but very limited tool for others. After all there is no perfect too. Every tool has some kind of limitation.
What people usually like the most about digital cameras is to be able to take as many pictures as they want and as their camera memory card will allow them. The good news is that you can also take pinhole photographs with your digital camera, by removing the lens and placing a cover with a small pinhole instead. It is not the same experience as using a camera obscure with film negative, but it is still pinhole photography.
If you want to play with pinhole cameras but is not in the mood to build one, you find many pinhole cameras makers out there.
To finish this post, I want to tell you that you still can use filters in front or inside the camera to manipulate image contrast, colours, light effects and so on, like in any other lensed camera.