Digital cameras work by saving images to a flash memory card then using compression to maximize the number of photos that can be stored on one card. Most cameras have a small amount of internal memory that is enhanced by adding the flash memory card.
Most digital cameras have and LCD display on the back of the camera, but it is helpful to also have an optical viewfinder. This is because the LCD uses a lot of battery power, and digital cameras are known for using lots of battery power. Exceptions to this would be extreme close-ups and pictures of large groups.