group of processes called banking stage
whenever a validator node becomes a leader, banking stage is responsible for processing of txns a component of this stage is called solana transaction scheduler
A validator is a Solana node that helps secure the network by i) producing blocks and ii) voting on the validity of other blocks. Recall that all Solana nodes keep track of the state of the blockchain. As a result, if a validator produces a faulty block, other validators will detect it and vote accordingly.
Solana gets around this by introducing a new type of node that still keeps track of all information on the blockchain but doesn’t vote on it or produce blocks. In other words, this node type — an RPC node — only responds to data requests and does not participate in consensus
Solana Nodes — A Primer on Solana RPCs, Validators, and RPC providers