Introduction

Proof of Stake as Sybil Protection

Proof of Stake (PoS) is fundamentally a Sybil protection mechanism that secures blockchain networks by preventing malicious actors from gaining control through the creation of multiple fake identities. Sybil protection mechanisms serve three critical functions:

1. Determine who gets to participate fairly - Establish clear rules for network participation
2. Ensure participation power is tied to scarce resources - Link voting power to valuable assets like stake, computation, or verified identity
3. Act as the gatekeeper - Control who can participate in consensus or block production

In Avalanche's implementation, PoS ties participation power to economic stake (AVAX tokens), making it prohibitively expensive for attackers to gain majority control of the network.

How Proof of Stake Works on Avalanche

Avalanche uses Proof of Stake with support for delegation to secure its network. Here's how it operates:

Validator Staking

Validators must stake AVAX tokens to participate in consensus. The requirements include:

• Minimum validator stake: 2,000 AVAX on Mainnet
• Staking duration: Between 2 weeks and 1 year
• Uptime requirement: Default 80% uptime to receive rewards

Delegation

Token holders who don't want to run a validator node can delegate their stake to existing validators:

• Minimum delegator stake: 25 AVAX on Mainnet
• Delegation fees: Validators charge a minimum 2% fee and share rewards with delegators
• Flexible participation: Anyone can delegate without running infrastructure

Validator Weight

A validator's influence in consensus is determined by their validator weight, which is the sum of:

• Their own staked tokens
• All tokens delegated to them by others

This weight determines how much influence they have during the consensus polling process.

Staking Lifecycle

1. Submission: Validators or delegators submit staking transactions with a specified duration
2. Pending: Stake enters a pending state until the start time
3. Active: Validators participate in consensus and earn rewards
4. Completion: At the end of the staking period, rewards are distributed and stake is unlocked

Consensus Participation

Validators with sufficient stake participate in Avalanche's consensus mechanism by repeatedly polling small random samples of other validators, weighted by their stake. The consensus algorithm itself—including Snowman consensus for linear chains—is covered in detail in the Avalanche Consensus section.

Unlike traditional Delegated Proof of Stake (DPoS) systems where a fixed number of delegates are elected, Avalanche allows anyone meeting the minimum stake requirement to become a validator. There's no voting mechanism to elect validators—participation is purely stake-based, making it more permissionless and decentralized.