Avalanche is a public blockchain and smart-contract platform launched in September 2020 by the American company Ava Labs. The platform's native cryptocurrency is AVAX.

Avalanche's primary network consists of three interoperable blockchains: the Exchange Chain (X-Chain), the Contract Chain (C-Chain), and the Platform Chain (P-Chain). These chains are used for asset transfers, smart-contract execution, and validator coordination, respectively.

The Avalanche consensus protocol was first described in a May 2018 whitepaper published pseudonymously under the name "Team Rocket." A group of researchers from Cornell University, including Emin Gün Sirer, expanded on this description. Sirer and two PhD candidates formed the company Ava Labs to develop the blockchain for use in the financial industry. The Avalanche network is backed by the non-profit organization, the Avalanche Foundation.

In March 2020, Ava Labs released the Avalanche codebase as open-source. In July 2020, Avalanche raised $42 million in less than five hours during the first public sale of its digital currency token.

In September 2021, the Avalanche Foundation secured a $230 million investment from a consortium including Polychain Capital and Three Arrows Capital by purchasing AVAX.