Summary Introduction Blockchain for beginners Traditional Banking Decentralized Banking Blockchain Properties Message order Ownership Transfer Read and write access No message modification Blocks Node Types Is Bitcoin a Decentralized Currency? Centralized Processes in Bitcoin Bitcoin Services Protocol Maintenance and Modifications Coin Tainting Enhancing the Decentralization in Bitcoin Part II Basics Crytography Hash Functions Merkle Tree Elliptic Curve Signature Consensus Mechanisms Mining and Proof of Work Proof of Stake Proof of Authority Network Communication Part III Permissionless Blockchains Bitcoin Bitcoin Transactions Bitcoin Script Bitcoin Blocks Ethereum Transactions Smart Contracts Solidity Monero Mimble Wimble Security Hardware Layer Network Layer Eclipse Attacks Blockchain Layer Double-Spending Selfish Mining Smart Contract Layer Privacy Tokens Scaling Payment Channels How decentralized are permissionless blockchain? Part IV Permissioned Blockchains Hyperledger Part V Do you need a blockchain? Use Cases International Payments Supply Chain Management Healthcare Electricity Production Part VII Research Challenges Further resources Acknowledgements Conclusions