Public Keys and Private Keys

This lesson covers the cryptography that lets you own and move crypto without a bank: public keys, private keys, and the digital signatures that prove a transaction is really yours. We build the idea on an everyday example first, then map it onto the blockchain. We close on the question that turns this from a technical curiosity into a trading-desk concern: who actually holds the keys, and what happens when it is not you. That question, “not your keys, not your coins,” reframed as custody and counterparty risk, runs through the rest of the course.