What the MetaMask Extension does
The MetaMask Extension is a browser wallet that securely stores private keys, signs transactions locally, and acts as a connection bridge between your browser and decentralized applications (dApps). It supports multiple Ethereum-compatible networks (Ethereum, Polygon, Optimism, Arbitrum, etc.), token management, and in-extension swaps.
Security fundamentals
MetaMask is designed to keep private keys on your device. Transactions must be approved manually, and the extension isolates dApp requests so sites cannot directly export your keys. That said, security also depends on user behavior. The following practices drastically reduce risk:
- Store your 12/24-word recovery phrase offline — never share it or type it on random websites.
- Use a strong, unique password for the extension and consider a hardware wallet (e.g., Ledger, Trezor) for large balances.
- Only approve transactions you recognize and always verify destination addresses and gas values.
- Keep your browser and extension updated — security patches matter.
How to install & set up
- Open your browser’s official extension store (Chrome Web Store, Firefox Add-ons, Edge Add-ons).
- Search for “MetaMask” and confirm the publisher is Consensys or the official MetaMask listing — check reviews and the number of users.
- Click Add to browser, then open the extension and choose Create a Wallet or Import using Secret Recovery Phrase.
- Write down the recovery phrase on paper and store it offline; do not screenshot it or keep it in cloud storage.
If you plan to use multiple networks, add them from Settings → Networks. Use reputable RPC endpoints or the built-in defaults.
Core features
- Account management: Create multiple accounts and manage addresses.
- dApp connectivity: Approve per-site connections and control permissions.
- Token management: Add custom tokens or import using contract addresses.
- Swaps: In-extension token swaps aggregate liquidity and preview slippage and price impact.
- Hardware wallet support: Connect Ledger/Trezor for secure transaction signing.
Daily usage & best practices
For safe day-to-day interactions:
- Use separate accounts for routine dApp activity and for long-term storage.
- Limit approval allowances — revoke approvals for sites you no longer use.
- Check transaction details in MetaMask before approving; copy-paste addresses to verify.
- When in doubt, use a read-only view (e.g., Etherscan) to confirm balances and transactions.
Troubleshooting common issues
Extension not appearing: Pin the extension from the browser toolbar or reinstall from the official store.
Missing funds: Confirm network selection (e.g., Mainnet vs Testnet). If your wallet is lost and you have the recovery phrase, import it in a fresh MetaMask install. If you lack the phrase, recovery is not possible.