The Camera

The "camera obscure" effect is a tiny hole created in one wall. The hole acts like a lens, focusing and projecting light (upside down) on the other wall. 
In the 17th Century, Isaac Newton and Christian Huygens perfected the understanding of optics and the process of making high quality glass lenses.
In 1827 Niepce created the "film" which created the first successful photograph.
Modern digital cameras are still very similar to old cameras in the way that light passes through the lens, into the camera, and exposes the film in both. Digital cameras use electronic sensor called a CCD or a digital film to capture an image. This makes the photography cheaper and more environmentally friendly.  
On a modern digital camera, the difference between Auto and Program is that Auto will automatically take a photo without you having to adjust the flash or any other settings, however, the Program button will allow you to adjust the flash setting and/or most other camera settings before taking the picture. The Portrait mode will attempt to blur out the surroundings and focus on the person/focal point. It does this by using the fastest available lens (aperture). The sports mode is used to freeze motion by using the highest shutter speed available. By half-pressing the shutter release button, it allows the camera to focus the image before you take the shot.

The 'No Flash" symbol, or the one where the lightning bolt is crossed out, means that the flash is off no matter what. You would use this when there is enough light in your image, or to create a more dramatic image. The flash symbol with the word AUTO on it means that the flash will only go off when the lighting is not great. You would use this in either situation because it's used when pictures are dark or light. If there's too much light in your photo the image will be washed out, and if there's not enough light the image will be too dark. The term "stop" represents a relative change in the brightness of light. If the planet has two suns instead of one that;s plus one stop, and if it has four suns then that's plus three stops. A long shutter speed equals more light, and a fast shutter speed has less light. The aperture controls the amount of brightness passing through the lens. To increase the amount of light you would need to create a larger opening.