What is Polkadot?
Polkadot (DOT) is a Layer-0 protocol designed to connect specialised blockchains ('parachains') into a single, shared security network. It was founded by Gavin Wood, one of Ethereum's original co-founders and the author of the Ethereum Yellow Paper, and launched its mainnet in 2020.
Instead of building a single chain that does everything, Polkadot provides a relay chain that secures and routes messages between up to 50 parachains. Each parachain can be customised for a specific purpose - DeFi, privacy, identity, gaming - but inherits the relay chain's validator set and finality guarantees.
How does Polkadot work?
Polkadot uses a nominated Proof-of-Stake model. Validators secure the relay chain and every parachain simultaneously, and DOT holders can nominate validators with their stake to earn rewards. Parachains are added via a process called coretime (formerly parachain slot auctions), where projects bid DOT for a predetermined amount of block space.
Cross-chain communication is handled by XCM, a format-agnostic message passing standard that lets parachains send assets and arbitrary instructions to each other. This gives Polkadot's ecosystem the flavour of a 'multi-chain, one-trust-zone' design that differs meaningfully from general-purpose smart-contract chains.