What is restaking and how EigenLayer turns staked ETH into shared security

Introduction Ethereum’s shift to proof of stake in September 2022 created a pool of economic security: over 30 million ETH staked by validators who risk losing their deposit (slashing) if they behave maliciously. This security pool protects Ethereum, but it sits idle with respect to every other protocol. New protocols that need decentralized validation face a bootstrapping problem. An oracle network, a data availability layer, or a cross-chain bridge needs validators, and those validators need economic stakes large enough to make attacks unprofitable. Building this security from scratch is expensive. Each new protocol must attract its own set of stakers, issue its own token for staking rewards, and hope that enough capital commits to make the system secure. Restaking proposes a different model. Instead of building independent security, new protocols borrow it from Ethereum. Stakers who already have ETH committed to Ethereum’s consensus opt in to additionally securing other services. The same capital backs multiple protocols simultaneously. EigenLayer formalized this concept and built the infrastructure for it. This guide explains how restaking works, what EigenLayer introduced, and...