What Is a Relay Chain?

The Relay Chain is the central chain that is used by the Polkadot network. Polkadot is a heterogeneous multi-chain and translation architecture that allows specialized blockchains and public blockchains to connect within a unified network.

The Relay Chain has deliberately minimal functionality, so, for example, smart contracts are not supported. The main task here is to coordinate the overall system and its connected parachains – the term for the  various individual layer 1 blockchains that run in parallel on the network.

All of the validators of Polkadot stake the network’s native DOT tokens and validate the Relay Chain. The architecture allows for a number of transaction types that allow validators to interact with governance mechanisms, parachain auctions, and nominated proof-of-stake (NPoS). 

Polkadot can support a number of execution slots, which are like scores on a CPU. Each of these can run one process at a time. Polkadot facilitates these slots using two subscription models:  parachains and parathreads. Parachains have a dedicated slot for their chain and are a process that runs constantly. Parathreads share slots among a group and are processes that only need to be called upon occasionally. As a result, they run a lot less frequently.

This being the case, most of the computation that occurs across the Polkadot network will be delegated to a specific parachain or parathread implementation, which can handle a particular use case. Polkadot places no constraints over what parachains are able to do besides the fact they must be able to generate a proof that can be validated by the validators that are assigned to the parachain.