Metamask Login: How to blockchain wallet FAQs | MetaMask

MetaMask keeps your wallet data private unless you authorize permission to share your account address. You will see a MetaMask confirmation when websites request access to view your account address.

MetaMask is an extension for accessing Ethereum enabled distributed applications, or "Dapps" in your browser! Watch an introductory video here. The extension injects the Ethereum web3 API into every website's javascript context, so that dapps can read from the blockchain.