MetaMask is an extension for accessing Ethereum enabled distributed applications, or "Dapps" in your browser! The MetaMask extension injects the Ethereum web3 API into every website's javascript context, so that dapps can read from the blockchain. MetaMask is a browser plugin, available as the MetaMask Chrome extension or Firefox Add-on. At its core, it serves as an Ethereum wallet: By installing it, you will get access to a unique Ethereum public address, with which you can start sending and receiving ether or tokens.