How Proof-of-Stake works

1
Becoming a TON network validator takes starting a specific software.

Anyone can do it; the more validators the better for the network.

An important prerequisite though is a high-performance server with strong connection operating 24/7.
2
A validator stakes their Toncoins for a specific term. This stake is paid back at the completion of a validation round with a surplus or validator reward for the effort.

Should a validator attempt to cheat or stay idle, their stake is fully or partially taken as a penalty.
3
Network validators verify user transactions. If all validators achieve consensus that a transaction is valid, it is included into the Blockchain. Invalid transactions are rejected.
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Therefore, validators have to correctly process user transactions at maximum speed to get rewarded and avoid penalties.
Open Documentation

How validators achieve consensus

An ad hoc Byzantine Fault Tolerant Catchain protocol was developed to ensure that stakeholders achieve consensus as long as the number of cheaters among them is 1/3 or less.

Also, the protocol provides mathematical proofs of cheating attempts that is used as evidence for imposing penalties.

Validators reward

A user adds a small surplus amount in Toncoins that represents a fee paid to validators as a reward for their work. Reward is distributed proportionally to the effective stakes of the validators.

Additionally, new Toncoins are generated during validation. These also go to validators. Overall annual coin inflation is about 0.6%.

What if a validator tries cheating?

By design, any cheating attempt in the Catchain Protocol is instantly detected. Upon the receipt of a mathematical proof of cheating, other validators immediately stop interacting with a cheater node. Then validators hold an automated vote to fine the cheater that consequently loses its stake fully or partially.

What if a validator underperforms or fails?

Each validator tracks processing statistics of other validators. If the number of transactions processed per period is too small for a particular node, validators collectively vote to fine it and it loses its stake fully or partially

Summary

1
Validators maintain the system operations.
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Any modification of the TON Blockchain requires consensus of all validators.
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An inevitable penalty for cheating forces validators to comply with the consistent rules