Blockchain is the underlying technology behind cryptocurrencies bringing together Merkle trees, Hashing & Distributed Architecture. Christopher Ellis explains. Note1 - At 6:46 when Chris is drawing the Merkle Tree, C would actually be duplicated and hashed with itself not with B. So you would get H(C - C) instead of H(B - C). Note2 - At minute 17, Christopher mentioned the mining reward halving at 21,000 bitcoins but meant 210,000 blocks. Public Key Encryption: https://www.youtube.com/watch?v=GSIDS_lvRv4 The Perfect Code: https://www.youtube.com/watch?v=WPoQfKQlOjg http://www.facebook.com/computerphile https://twitter.com/computer_phile This video was filmed and edited by Sean Riley. Computer Science at the University of Nottingham: http://bit.ly/nottscomputer Computerphile is a sister project to Brady Haran's Numberphile. More at http://www.bradyharan.com/