We may not have the equipment in the future to read the storage systems we use today. While film will generally keep well under the right temperature, humidity and light conditions, digital information may require routine copying onto new media in order to preserve it. A pixel can be thought of as being a spot of complex colour made up by combining a series of smaller spots of simple colour called a bit. Bits are primary colours such as red, green and blue. Each pixel can be thought of as a patch or spot of colour which gets it's characteristic colour from the way in which the bits it incorporates are combined.
Different pixels are different colours.
The more bits in a pixel, the greater the ability to manipulate and obtain better quality images. Many scanners and digital cameras actually have the capacity to deal with more than 24 bits per channel. A black and white image only requires one channel for brightness. CMYK is the system used in the printing industry. Virtually all printers use a four ink system, meaning that a conversion needs to happen to get a print out.