1. How Blockchain Works — blockchain.mit.edu

A blockchain is a way for a network of computers to agree on a shared record without trusting any single party. This seven-step demo builds one up from scratch: first a hash, then a block, then a chain of blocks, then the same chain distributed across peers, and finally tokens and coinbase transactions — the ingredients of Bitcoin.

Watch the introduction below, then step through the interactive pages using the numbered navigation. Everything runs in your browser — type in any field and watch the hashes change.

This interactive demo was created by Anders Brownworth and is rebuilt here as a self-hosted, dependency-free version. SHA-256 runs entirely in your browser; blocks turn red when their hash no longer starts with 0000 and green again once re-mined.