Principles of Consensus

The principles and assumptions of consensus algorithms can be more clearly understood by asking a few key questions:

• Who can change the past, and how? (This is also known as immutability.)

• Who can change the future, and how? (This is also known as finality.)

• What is the cost to make such changes?

• How decentralized is the power to make such changes?

• Who will know if something has changed, and how will they know?

Consensus algorithms are evolving rapidly, attempting to answer these questions in increasingly innovative ways.