Optimistic Finality
Optimistic finality is a consensus approach that assumes transactions are valid unless proven otherwise, allowing for faster processing. In this model, blocks are considered final after a challenge period, during which participants can submit evidence of fraud.
If no fraud is detected, the transaction remains permanent; if fraud is proven, the transaction is reverted and the malicious actor is penalized. This mechanism is widely used in Layer 2 scaling solutions like optimistic rollups.
It allows for high throughput because the heavy computation of verification is only performed when a dispute arises. While it introduces a delay for withdrawals, it significantly improves the efficiency of everyday transactions.
It represents a pragmatic trade-off between speed and the necessity of verification.