Slashing

Slashing is a penalty mechanism in proof-of-stake networks that destroys a portion of a validator's staked tokens when the validator provably breaks protocol rules. It is the enforcement arm of staking: rewards encourage honest participation, while slashing makes attacks and serious negligence financially painful. Typical slashable offenses include double-signing — approving two conflicting blocks at the same height — and, on some chains, extended downtime.

A concrete example: on Ethereum, a validator caught signing two contradictory attestations is slashed, losing part of its 32 ETH stake and being forcibly ejected from the validator set; penalties scale up if many validators commit the same offense simultaneously, which is designed to make coordinated attacks ruinously expensive. In practice, most real-world slashing events have been caused not by malice but by misconfiguration, such as running the same validator key on two machines for redundancy.

A common misconception is that ordinary stakers are immune because they did nothing wrong — if you delegate to a validator or use a staking pool, a slashing event at that operator can reduce your tokens too, depending on the protocol and the provider's terms. This is why validator reliability and operational practices matter when choosing where to stake, not just the advertised reward rate.