Glossary
Restaking
Re-using already-staked ETH (or a liquid-staking receipt) as security for additional services, in exchange for additional yield and additional slashing risk.
Restaking — popularized by EigenLayer — lets a validator opt their existing stake into securing other services: oracles, bridges, data-availability layers, rollups, sidechains. The extra services pay the validator additional yield, but they can also slash for misbehavior.
The bet is that one ETH bond can secure many things; the criticism is that correlated failures could compound across protocols. Either way, restaking adds a new layer of "AVS" — actively validated services — on top of base consensus.