Huffman coding
From Just Solve the File Format Problem
Huffman coding is a kind of lossless data compression.
Symbols (such as bytes) are encoded as variable-length bit strings, optimized such that the more common symbols use shorter bit strings. No bit string is allowed to be a prefix of another bit string, which makes it possible for the decoder to deduce when a string has ended.
The code table used may be stored in the compressed file, or it may be a predefined table known to both the encoder and decoder.
