How do we derive the most compact codes for a situation? Huffman Trees can help. Professor Brailsford explains how computer scientists like their trees to be upside down. "Entropy in Compression - Computerphile" precedes this: http://www.youtube.com/watch?v=M5c_RFKVkko EXTRA BITS: More on Huffman Trees: http://www.youtube.com/watch?v=DV8efuB3h2g Error Correction: http://www.youtube.com/watch?v=