> ## Documentation Index
> Fetch the complete documentation index at: https://docs.theblockchainlibrary.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Consensus

> Understand how blockchain networks agree on valid state without relying on one central database.

## Why consensus exists

Distributed networks need a method for deciding which transactions are valid, how they are ordered, and which version of network state participants should accept.

## Common models

Proof of Work and Proof of Stake are widely known consensus families, but implementations vary substantially. Networks may also use BFT-style protocols, validator committees, delegated designs, or hybrid systems.

## What to evaluate

When comparing consensus systems, consider security assumptions, validator incentives, finality, fault tolerance, hardware requirements, decentralization, and governance—not only transactions per second.