Arbitrum is a layer-two (L2) scaling solution built on top of the Ethereum blockchain. It employs optimistic rollups to achieve faster speeds, improved scalability, and greater cost-efficiency on Ethereum. By offloading most of the computational and storage load off-chain, Arbitrum benefits from Ethereum's security and compatibility while providing higher throughput and lower fees compared to Ethereum.

The native token of the Arbitrum ecosystem is called ARB, which is primarily used for governance. Offchain Labs, the team behind Arbitrum, recently announced the transition to a decentralized autonomous organization (DAO) structure known as the Arbitrum DAO. ARB holders have the power to vote on proposals that impact protocol upgrades, features, fund allocation, and the selection of a Security Council.

In 2023, Arbitrum has an ambitious roadmap that includes the launch of Orbit, its own layer-three solution, enabling developers to deploy programs in popular programming languages like Rust and C++ using Stylus, expanding its validator set to include more independent institutional validators, and moving its protocol to layer two with Arbitrum One.

On March 16, 2023, Arbitrum announced a highly anticipated airdrop of ARB. The token will be distributed to early users and DAOs building on the Arbitrum network, with 12.75% of the total supply to be distributed. Recipients were rewarded on a point-based system based on their interaction with the Arbitrum network until the cutoff date of March 1, 2023. The token generation event is scheduled for March 23, 2023.

Frequently Asked Questions on Arbitrum

1. How does gas work on Arbitrum chains?

A: Fees on Arbitrum chains are collected in the chains' native currency, which is ETH on both Arbitrum One and Nova. The transaction fee consists of both an L1 and an L2 component. The L1 component compensates the Sequencer for the cost of posting transactions on L1, while the L2 component covers the cost of operating the L2 chain. Unlike Ethereum, Arbitrum chains enforce a gas price floor, currently 0.1 gwei on Arbitrum One and 0.01 gwei on Nova. L2 gas price adjusts responsively to chain congestion, similar to EIP 1559.

2. Why does it look like two identical transactions consume a different amount of gas?

A: An Arbitrum node's eth_estimateGas RPC returns a value sufficient to cover both the L1 and L2 components of the fee for the current gas price. If the L1 calldata price changes over time, it will appear in a user's wallet that a transaction's gas limit is changing. In reality, the L2 gas limit isn't changing, only the total gas required to cover the transaction's L1 + L2 fees.

3. How is the L1 portion of an Arbitrum transaction’s gas fee computed?

A: The L1 fee that a transaction is required to pay is determined by compressing its data with brotli and multiplying the size of the result (in bytes) by ArbOS’s current call data price. The latter value can be queried via the getPricesInWei method of the ArbGasInfo precompile.

4. Does Arbitrum have a mempool?

A: The Arbitrum Sequencer orders transactions on a first come, first served basis, and inserts transactions into a queue based on the order they are received and executes them accordingly. This queue exists in lieu of a mempool and has no space limit. Transactions on the queue will eventually timeout and be discarded if not executed in time. Under normal conditions, the queue is empty, and transactions are executed near-instantaneously.

5. Do I need to pay a Priority fee for my Arbitrum transactions?

A: No, transactions are processed in the order that the Sequencer receives them, so no priority fee is necessary. If a transaction includes a priority fee, it will be refunded to the transaction’s origin address at the end of execution.