Arbitrum (ARB) is one of the largest Layer 2 networks scaling Ethereum — it processes transactions off the main chain and settles them back to Ethereum (an 'optimistic rollup'), making them far cheaper and faster while inheriting Ethereum's security. It's long been a leader in deep DeFi liquidity, hosting a mature ecosystem of exchanges, lending and other apps. It also offers 'Orbit', letting teams launch their own custom chains using Arbitrum's technology, making it more of a scaling framework than a single network. ARB is the governance token, used to vote in the Arbitrum DAO — but note that users pay gas in ETH, not ARB, so the token's direct utility is governance rather than fees.
Where it stands today: Arbitrum consistently ranks at or near the top of Ethereum Layer 2s, securing tens of billions of dollars in value, with a mature app base and growing real-world-asset activity. But it's no longer the automatic winner: Coinbase's Base has stronger consumer reach, and zk-rollups (Starknet, zkSync) appeal to others. Its biggest token challenge is ongoing supply — ARB unlocks run into 2027, steadily adding new tokens, and the token captures limited value since it's governance-only and gas is paid in ETH. The DAO does generate real sequencer revenue and holds a sizable treasury. So today it's a top-tier, DeFi-heavy L2 with strong fundamentals as a network, but a token weighed down by unlocks and weak value capture.