PolkadotDOT

Polkadot was conceived by Gavin Wood in 2016 — shortly after he left the Ethereum Foundation — as an alternative answer to the scalability question. Rather than scaling a single chain, Polkadot scales horizontally by hosting multiple specialized chains (parachains) that share security through the central relay chain. Each parachain can have its own runtime, consensus tweaks, and economic model while inheriting the security of the validator set as a whole.

Parachains are auctioned for time-bound slots in a model called crowdloan auctions, where projects bid by locking up DOT for the duration of their slot. The auction system caps the number of active parachains, which has been both an asset (rigorous filtering) and a constraint (limited slots compared to permissionless EVM chains). Major parachains include Acala (DeFi), Moonbeam (EVM compatibility), and Astar (multi-VM smart contracts).

DOT is used for staking (validating the relay chain), parachain auction collateral, and on-chain governance. The Polkadot 2.0 roadmap (rolling out through 2024-2025) replaces the auction model with "coretime" — a more flexible system letting parachains buy block-space on demand rather than locking DOT for two-year slots. The platform competes for the same multi-chain narrative as Cosmos but takes a more centralized approach to shared security in exchange for stronger cross-chain message guarantees.