The Avalanche blockchain enables near-instant transaction execution. AVAX is used to pay transaction fees, secure the Avalanche network, and serve as a basic unit of account among Avalanche blockchains.
The Avalanche protocol, which is known for its speed and scalability, is also a major competitor to the Ethereum network. Avalanche's smart contracts platform enables both decentralized applications and autonomous blockchains, and the company promises a faster transaction processing time of 4,500 transactions per second versus Ethereum's limit of around 15.
Here is a great resource for learning more about the Avalanche blockchain APIs.