Digital media is found in many forms. These forms include:The World Wide WebDigital Audio Digital Video Digital PhotosandDigital TV Transmission... etc.These forms of digital media can often be confused with the hardware that are used to hold them. For example, and piece of hardware used to access the World Wide Web would be a computer. An example of hardware for Digital Audio would be mp3 players or an i pod. etc.Their are two numbers used to code all digital data. These are 0 and 1. This coding system is called 'Binary System'. The binary language used by all digital media and can be translated to other languages. Binary digits are a basic unit of information storage.
A bit is a binary digit, taking a value of either 0 or 1. Consisting of 8 bits, a byte is capable of holding a single character and is a measurement of digital data. Sampling Rate determines the sound frequency range which can be represented in the digital waveform.
Colour Depth is a term that describes the number of bits used to represent the colour in a single pixel in bit mapped images or video frame buffers. The higher the quality of colour depth, the better and broader range of distinct colours that you have.

The reason colour depth affects both still and video digital media is that it is to do with the pixels in the images recorded, and both of these forms of digital media use pixles. Sampling rate only efects video because it is to do with audio and sound frequency, still images do not use sound.