The name given to the process of encoding data such that it uses lesser number of bits as compared to the original representation.
There are a number of techniques to compress information, with most algorithms working to compress image, speech, music or video. Encoding the same information in lesser bits results in saving some crucial resource such as transmission bandwidth or hard-disk space. Compression algorithms also take advantage of human perception to further reduce the size of information. By encoding the same piece of information with fewer bits in places that the human brain is not accustomed to perceiving as well as other parts, substantial gains in compression ratios can be achieved.