The purpose of channel coding is to maintain the frequency components in the data stream inside the bandwidth determined by the TX loop filter and RX filter.

Source Coding : this is done to reduce the size of the information (data compression) being transmitted and conserve the available bandwidth. This process reduces redundancy.

e.g. zipping files, video coding (H.264, AVS-China, Dirac) etc.

Channel Coding : this is done to reduce errors during transmission of data along the channel from the source to the destination. This process adds to the redundancy of data.

e.g. Turbo codes, convolutional codes etc.

Color coding is used to identify the channel.

actually the channel coding is used for the security of transmission of any digital data.

and it also determines the appropriate channel for the tranmission of your message on internet

For coding