How does a Digital camera take a picture?

when you look through the lens before taking the picture the image is actually being 'bounced' off several mirrors.

when you take the photo the mirrors fold back and are captured in the camera.

when you are finished taking the photo they go back intoplace so you can see through it again.

that is why when you take a photo there is that snapping noise. if you were to look through it at that moment you could probably see blackness for a split second because the mirrors have gone and then you can see it again because they are back.