Blockchain & Bitcoin

01Overview

In 2008 a pseudonymous Satoshi Nakamoto published the Bitcoin whitepaper; in 2009 the genesis block appeared. Bitcoin uses proof of work so miners compete for the right to write, the longest-chain rule to settle forks, and public-key addresses for pseudonymous payment. It was the first large-scale permissionless consensus system.

In 2013 Ethereum added smart contracts and turned the blockchain into a programmable state machine. DeFi, NFTs and Layer 2 scaling followed, along with fraud, energy use and regulatory argument. Whether blockchain delivers its promise is still debated, but the question it raises — how do mutually distrusting parties agree — is the central question of distributed systems.

02History

2008
The Bitcoin whitepaper
Permissionless consensus.
2009
The genesis block
The Bitcoin network starts.
2013
Ethereum
Smart contracts.
2015
Ethereum mainnet launches
A programmable blockchain.
2022
The Merge
Ethereum moves from proof of work to proof of stake.

03Core concepts

Hash chain

Each block contains the previous block’s hash, forming a tamper-evident chain.

Proof of work

Compete with compute for the right to write, raising the cost of misbehaviour.

Smart contract

A program deployed on chain that executes automatically.

04Hands-on

Do it once — it beats reading it ten times

Build a 100-line blockchain with proof of work and then rewrite a block to see the chain reject it

Tick this once you have built it and written down what you learned; the topic is then marked as built.

05Self-check

Say it in your own words first, then open the answer. Whatever you cannot explain is what to review next.

Can you explain "Hash chain"?

Each block contains the previous block’s hash, forming a tamper-evident chain.

Can you explain "Proof of work"?

Compete with compute for the right to write, raising the cost of misbehaviour.

Can you explain "Smart contract"?

A program deployed on chain that executes automatically.

What problem did it solve, and why was there nothing better at the time?

Go back to the history section: how was this done before, and what did it cost?

If you had to build it today, how would you break it down?

Use the hands-on task above: write a plan of at most three steps before you start.

06Key people

Satoshi Nakamoto

unknown

The anonymous creator of Bitcoin.

Vitalik Buterin

1994 –

Co-founder of Ethereum.

07Further reading

Bitcoin: A Peer-to-Peer Electronic Cash SystemSatoshi Nakamoto · 2008
Mastering BitcoinAndreas Antonopoulos · 2014