Arbitrum is designed to scale Ethereum, allowing transactions to be cheaper and faster. Its key feature is the ability to adjudicate and prove fraud on Layer 1, which is how it inherits Ethereum's security. Data fed into an Arbitrum Rollup chain is posted directly on Ethereum, providing visibility into Arbitrum activity. Validators move the Arbitrum chain state forward, and as long as there's one honest validator, the chain remains secure. If validators disagree, a dispute is narrowed down to a single computational step which is executed on Layer 1. Users typically have to wait 1 week to withdraw funds from Arbitrum to Ethereum, but fast-bridge applications can bypass this delay. Transactions are submitted on Layer 1 in batches, reducing transaction costs. Arbitrum was created with Ethereum compatibility as a top priority, meaning users can use Arbitrum with all their favorite Ethereum wallets and developers can build and deploy contracts with their favorite Ethereum libraries and tooling.

There are several SDKs available for developers to interact with the Arbitrum.

• Offchian Labs SDK
• Rust
• GO.

The Arbitrum API forms a bridge between applications and an Arbitrum node which is part of the Arbitrum network. Developers can engage with on-chain data and dispatch various kinds of transactions to the network by leveraging the API endpoints. The API adheres to a JSON-RPC standard, a stateless, lightweight, remote procedure call (RPC) protocol presented in JSON format.

Once you've created an API key with Dwellir you will have a unique RPC URL for the Arbitrum network. You can use this URL to connect to the network and start interacting with it.

Offchain Labs has developed Arbitrum One as a particular variant of the Arbitrum protocol, which is now active on Ethereum's primary network. Essentially, while Arbitrum One represents one iteration of the Arbitrum protocol, there could be more versions coming in the future.