All Lessons

What is a Blockchain?

Distributed ledgers vs. databases, the trust model, and why decentralization matters.

Blocks, Hashes, and Chains

How cryptographic fingerprints link blocks into a tamper-evident chain.

Distributed vs. Centralized Systems

P2P networks, Byzantine fault tolerance, and what 'trustless' really means.

Consensus Mechanisms

How strangers agree without trusting each other: Proof of Work vs. Proof of Stake.

Cryptographic Hash Functions

SHA-256, the avalanche effect, and why pre-image resistance is the foundation of mining.

Public Keys, Private Keys, and Addresses

Elliptic curve cryptography, digital signatures, and why losing a key means losing funds forever.

Symmetric Encryption

AES and shared-secret encryption: when the same key locks and unlocks.

Asymmetric Encryption

RSA and elliptic curves: one key to lock, another to unlock.

Digital Signatures

ECDSA and Schnorr: proving ownership without revealing secrets.

Merkle Trees

Efficient transaction verification using binary hash trees.

Zero-Knowledge Proofs

Proving you know something without revealing what you know.

The UTXO Transaction Model

How Bitcoin accounts work: unspent transaction outputs and change addresses.

Proof of Work: Mining Economics

Hash rate, difficulty adjustment, block rewards, and the halving cycle.

Mempool and Transaction Fees

How unconfirmed transactions compete for block space.

Bitcoin Script

Bitcoin's stack-based scripting language and common output types.

The Lightning Network

Payment channels, routing, and how Lightning scales Bitcoin off-chain.

The Ethereum Virtual Machine

How the EVM executes smart contract bytecode deterministically across all nodes.

Solidity: Smart Contract Language

Variables, functions, state, events, and the Solidity execution model.

Gas and Transaction Fees

Why gas exists, how EIP-1559 works, and how to optimize contract costs.

ERC-20, ERC-721, and Token Standards

Fungible tokens, NFTs, and the interfaces that make composability possible.

DeFi Primitives

AMMs, liquidity pools, lending protocols, and how DeFi rebuilds traditional finance.

51% Attacks and Chain Reorganization

How majority hash rate enables double-spends and what happened to Ethereum Classic.

Sybil and Eclipse Attacks

Manipulating P2P network topology to isolate and deceive nodes.

Smart Contract Vulnerabilities

Reentrancy (the DAO hack), integer overflow, access control, and static analysis.

MEV and Frontrunning

Maximal extractable value, sandwich attacks, and flashbots.

Private Key Security and OpSec

Hardware wallets, air gaps, seed phrase storage, and how people actually lose crypto.