What is an Optimistic Rollup?
An optimistic rollup is a rollup approach that verifies results through a specific dispute and fraud-proof mechanism.
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What is an optimistic rollup?
An optimistic rollup is a Layer 2 approach that executes transactions off-chain and allows proposed results to be challenged for inaccuracy. The word “optimistic” describes the idea that results are accepted unless proven otherwise within a specific period. This does not mean that no one checks the results.
Participants can recalculate transactions and compare them with the proposed result. If there is a discrepancy, the protocol’s fraud-proof mechanism can be triggered. Who can use the mechanism and how much of it is active depends on the current implementation of the network being used.
Why can withdrawals be delayed?
When exiting to the mainnet via an official bridge, a period may be allowed for challenging incorrect results. For this reason, a withdrawal to the mainnet may take longer than a transaction that appears within seconds inside Layer 2. This wait is not the same as a delay caused by exchange traffic; it can be part of the protocol’s security process.
For example, while sending tokens within a rollup happens quickly, there may be a stage lasting for days to withdraw them back to Ethereum. The exact duration should be learned from the network’s official bridge screen. It is not accurate to assign a single, unchanging duration to all optimistic rollups.
Does a fast bridge offer the same security?
Some services provide your assets on the target network early by providing liquidity before the waiting period is complete. In exchange, you may pay a fee and be exposed to additional smart contract or liquidity provider risks. Such a service does not magically eliminate the security stages of the official bridge; it offers a different transaction economically.
When choosing a network, look at how transactions are sent during sequencer downtime, admin keys, and upgrade authorities. The phrase “on Ethereum” does not mean that all components of the network carry the same security features as the Ethereum mainnet.