哈夫曼在上世纪五十年代初就提出这种编码时，根据字符出现的概率来构造平均长度最短的编码。它是一种变长的编码。在编码中，若各码字长度严格按照码字所对应符号出现概率的大小的逆序排列，则编码的平均长度是最小的。（注：码字即为符号经哈夫曼编码后得到的编码，其长度是因符号出现的概率而不同，所以说哈夫曼编码是变长的编码。）-Huffman in the early fifties of last century to make such a code, depending on the probability to construct the character average length of the shortest encoding. It is a variable length encoding. In the code, if the code length code word in strict accordance with the probability corresponding to the size of symbols arranged in reverse order, the average length of code is the smallest. (Note: The code word is the symbol obtained by the Huffman encoding, and its length is the probability for the different symbols, so that the Huffman coding is a variable length encoding.)