MetaMask is a browser extension and cryptocurrency wallet that allows users to interact with the Ethereum blockchain. It allows users to run [[dApps:dApps (decentralized applications)]] directly in their browser. MetaMask also allows users to manage their Ethereum accounts, including sending and receiving Ether and other Ethereum-based tokens. It is an important tool for users who want to participate in the Ethereum ecosystem and use dApps.

While MetaMask is primarily known for its support for the Ethereum blockchain, it also supports other blockchain networks that are based on Ethereum, such as [[Optimism]], [[Polygon]], and [[Avalanche]]. In addition, MetaMask also allows users to connect to custom Ethereum-based networks and nodes, which enables users to interact with any Ethereum-compatible blockchain. However, MetaMask does not support blockchains that are not based on Ethereum, such as [[Bitcoin]] or [[Solana]].