A consensus mechanism is the protocol through which distributed network participants agree on valid transactions, ordering, and the authoritative state of a blockchain or distributed ledger.
Consensus protocols define how participants propose, verify, order, and finalize updates despite network delays, faulty participants, or adversarial behavior. Proof of work and proof of stake are two widely used families, but many variants exist. Consensus design affects security assumptions, confirmation behavior, finality, throughput, energy use, and the incentives faced by block producers or validators.
Consensus determines agreement on ledger state. Transaction validation checks whether an individual transaction follows the protocol's rules; validation is one component of the broader consensus process.
Stablecoin transfers inherit the security and settlement properties of the network's consensus mechanism.
A proof-of-stake blockchain can require validators to attest to proposed blocks and use those attestations to determine the canonical ledger state.