MetaMask allows interaction with Ethereum blockchain via Firefox and Chrome browsers. It injects a web3 object within the running websites' JavaScript context which allows immediate interface capability for DApps. This injection allows DApps to interact directly with the blockchain.
MetaMask also allows account management. This acts as a verification method before any transaction is executed on the blockchain. The user is shown a secure interface to review the transaction for approval or rejection before it can reach the target blockchain.
It allows connectivity with various Ethereum networks as shown in the following ...