The main Polkadot blockchain, called the “Relay Chain” is where transactions are finalized. To achieve a greater speed, this main chain separates the addition of new transactions from the act of validating those transactions. This model allows Polkadot to process over 1,000 transactions per second. Parachains on the other hand, are custom blockchains that use the relay chain’s computing resources to confirm that transactions are accurate.
Another interesting functionality of Polkadot is its bridges as these allow the Polkadot network to interact with other blockchains and thus allow for tokens and coins to be swapped without an exchange.