This was a great video intro to the blockchain.

In short, blockchain is a immutable linked list of hashes. Which can be used to solve the double spending problem in cryptocurrencies using proof of work and a persistent chain of records (blocks mined).

Consensus algorithms

  • PoW: The more hashing power the more trust worthy.

  • PoS: The more coins the more trust worthy.

  • PBFT: Hand selected trusted nodes.

  • Randomized asynchronous algorithm: You trust nobody! Every single node is constantly re-evaluated. (Skycoin)

Interesting applications

  • Horizon State - Digital voting.

  • Blockstack - Decentralized apps on Blockstack let you own your data so you can maintain your privacy, security and freedom.

  • Cardano - Cryptographic currency implementing Ouroboros PoS protocol.

  • Iden3 - Decentralized identity management solution.