Source : Free On-Line Dictionary of Computing

Huffman coding
     
         A {data compression} technique which varies the
        length of the encoded symbol in proportion to its information
        content, that is the more often a symbol or token is used, the
        shorter the binary string used to represent it in the
        compressed stream.  Huffman codes can be properly decoded
        because they obey the prefix property, which means that no
        code can be a prefix of another code, and so the complete set
        of codes can be represented as a binary tree, known as a
        Huffman tree.  Huffman coding was first described in a seminal
        paper by D.A. Huffman in 1952.
     
        (1994-12-23)