Architecture of Polkadot
Polkadot utilises a central chain called the relay chain which communicates with mul- tiple heterogeneous and independent sharded chains called parachains (parallel chains). The relay chain is responsible for providing shared security for all parachains, as well as trust-free interchain transactability between parachains. In other words, the issues that Polkadot aims to address are those discussed above: interoperability, scalablility, and weaker security due to splitting the security power.