MetaMask is a self-custody software crypto wallet you run as a browser extension or a phone app. It launched in 2016, built by ConsenSys, and it is the wallet most people meet first when they start using apps that run on Ethereum. Self-custody is the part that matters: you hold the keys, so you control the funds, and no company can move them or freeze them for you.
When you set up MetaMask, it generates a 12-word Secret Recovery Phrase, also called a seed phrase. That phrase is the master key to every account in the wallet. Write it down, store it offline, and never type it into a website or hand it to anyone. The password you set only unlocks the app on that one device; the recovery phrase is what restores the wallet anywhere. Lose it with no backup and the funds are gone, because there is no support desk that can reset it.
How it works
The wallet holds your keys and signs transactions; the blockchain does the rest. MetaMask started on Ethereum and the EVM chains that share its format, the Polygon, Arbitrum, Base, and Optimism layer-2 networks among them, and has since added Solana and Bitcoin under a single account. You can view balances across those chains in one place and swap or bridge between them inside the app.
Its real job is acting as the gateway between you and on-chain apps. Visit a decentralized exchange, an NFT marketplace, or a lending protocol, click connect, and MetaMask pops up to approve the connection and sign each action. Nothing happens to your funds until you approve it, which is the point of self-custody, and also the point where people get caught.
What it's good for
MetaMask earns its place as a daily driver for on-chain work. If you trade on a decentralized exchange, supply liquidity, mint or buy NFTs, or interact with DeFi protocols across several chains, it is the wallet those apps expect and support. The connect flow is near-universal in the EVM world, so you rarely hit an app it cannot talk to.
For a beginner who wants to actually use Ethereum apps rather than just hold a coin on an exchange, it is a sensible first software wallet. The setup is quick and the app walks you through it. We cover that flow step by step in how to set up MetaMask.
The honest tradeoffs
MetaMask is a hot wallet, meaning the keys live on an internet-connected device. That convenience is also the attack surface. Malware, a fake browser extension, or a phishing site that tricks you into signing the wrong thing can drain a hot wallet, and the loss is final. Self-custody removes the bank, and it removes the safety net with it.
The most common way people lose money here is not a hacked seed phrase. It is a token approval. Connecting to a malicious or spoofed app and approving a transaction can hand it permission to move your tokens later. Read what you are signing, treat unlimited approvals with suspicion, and revoke approvals you no longer use. More on spotting the setups in our crypto safety guide.
For anything beyond pocket-money amounts, pair MetaMask with a hardware wallet such as the Ledger Nano X. The keys then stay on the offline device and you confirm each transaction by pressing a physical button, so malware on your computer cannot sign for you. You still use the MetaMask interface; the signing just moves somewhere a phishing page cannot reach. Our Ledger vs MetaMask comparison walks through when each one fits.