More precisely, a Consensus protocol must satisfy the four formal properties below.
* '''Termination''': every correct process decides some value.
* '''Validity''': if all processes propose the same value <math>v</math>, then every correct process decides <math>v</math>.
* '''Integrity''': every correct process decides at most one value, and if it decides some value <math>v</math>, then <math>v</math> must have been proposed by some process.
* '''Agreement''': if a correct process decides <math>v</math>, then every correct process decides <math>v</math>.
A typical algorithm for solving consensus is the [[paxos algorithm]].
