Slashing is a form of penalty on Proof of Stake (PoS) networks implemented to ensure accountability.

What Is Slashing?

Slashing is a form of penalty on Proof of Stake (PoS) networks implemented to ensure accountability. The bad actors are penalized and fined a percentage of their staked amount for their offense. 
The PoS system encourages security and protection by rewarding validators for performing their job well and holding them accountable for their negligence.

How Does Slashing Work?

Slashing policies vary from network to network. Ethereum Merge was recently implemented to adopt the Proof of Stake mechanism. Now, Ethereum 2.0 has validators instead of miners. These validators get rewarded for staking their coins to keep the network secure. However, when validators fail to perform their job, they get slashed.

Active Network Actors, behaving as whistleblowers, catch an offender. They then construct an infringement statement against the bad validator and add it to a new block. The validator is then penalized for their offense. The punishment usually invalidates their validator id and makes them pay an amount depending on the number of validators involved. The bigger the number, the greater the penalty imposed on the staked amount. The whistleblower is rewarded a fraction of the collected amount from penalties.

What Causes Slashing?

In most networks, crypto slashing is triggered by either double signing or validator downtime. Double signing can result in a significantly greater percentage of penalty, reaching 5%, while downtime often results in a small penalty of 0.1% of tokens. Slashing can occur when two different blocks are signed for the same slots, when validators contradict each other, or when they sign two simultaneously to initiate a validation. 

How to Prevent Slashing?

To avoid crypto slashing, users should never simultaneously run identical validating keys in two or more places. Accept downtime and avoid over-engineering validator setups. Some users will keep a backup while running their main validator to avoid going offline if their main validator experiences technical glitches. This helps validators keep profitability, but it’s not worth it because you’re continuously at risk of double signing a block.