Blockchain Fundamentals: Structure and Transactions

This lecture covers the fundamental concepts of blockchain technology, including the decision-making process of whether to use a blockchain or a database, the structure of blockchain blocks, the key idea of Proof-of-Work, the assumptions underlying blockchain security, and the differences between UTXO and account-based transactions. It also delves into Bitcoin transactions, scripting, limitations, and Ethereum smart contracts, discussing gas, execution time, and applications like trustless insurance and decentralized naming. The lecture concludes with a look at the issues and limitations of smart contracts, proposing solutions such as keeping secrets off-chain and permissionless innovation.