MetaMask connects users to decentralised applications (dApps) by acting as a bridge between a blockchain and the web browser. Normally, web browsers cannot directly interact with blockchain networks like Ethereum. MetaMask solves this by serving as both a wallet and a gateway, allowing users to manage their private keys and sign transactions while browsing dApps seamlessly.

When a user installs MetaMask as a browser extension or mobile app, it injects a web3 API into the browser. This makes it possible for dApps to detect MetaMask and request permissions. For example, when visiting a decentralised exchange, the site may prompt the user to “Connect Wallet.” Once approved, the dApp can view the wallet’s public address and interact with the blockchain on behalf of the user. Importantly, MetaMask never exposes private keys to the dApp. Instead, it asks the user to approve or reject every transaction through a secure interface.

MetaMask also allows switching between networks, such as Ethereum Mainnet, testnets, or other supported blockchains like Polygon or Binance Smart Chain. This flexibility gives users access to a wide range of dApps, from DeFi platforms to NFT marketplaces.

In short, MetaMask works as a secure intermediary. It gives dApps the ability to communicate with blockchains, while keeping control of the wallet and funds firmly in the hands of the user.