Blockchain

The blockchain core beneath coins and smart contracts: a validated transaction log, an authenticated state commitment, and deterministic rules that every full node re-executes independently.

How Ethereum's execution client, proof-of-stake consensus client, authenticated world state, EVM, transaction gossip, discovery, and RLPx transport fit together after the Merge.

A byte-to-state account of Bitcoin payments: UTXOs and outpoints, transaction serialization, locking and unlocking conditions, signature digests, SegWit, Taproot, identifiers, fees, and the boundary between consensus and relay policy.

How Bitcoin nodes discover peers, establish v1 or v2 transport, announce and fetch transactions and blocks, apply relay policy, and converge through validation and chainwork rather than trusting the network connection.

How proof of work, the most-cumulative-work rule, and economic incentives let an open membership network converge without finality certificates—and why confirmations reduce rather than eliminate reorganization risk.

How IBC uses on-chain light clients, authenticated commitments, connections, channels, relayers, packets, acknowledgements, and timeouts to move verified state between independent chains.