The document discusses Huffman coding, which is a lossless data compression algorithm that uses variable-length codes to encode symbols based on their frequency of occurrence. It begins with definitions of Huffman coding and related terms. It then describes the encoding and decoding processes, which involve constructing a Huffman tree based on symbol frequencies and traversing the tree to encode or decode data. An example is provided that shows the full process of constructing a Huffman tree for a sample frequency table and determining the Huffman codes, average code length, and total encoded length.