How MetaMask Works

Private Keys and Addresses

MetaMask is based on public-key cryptography:

• Secret Phrase (Seed Phrase) — 12 words generated when creating the wallet. This is the master key to all your assets.
• Private key — unique key for each wallet address. Allows signing transactions.
• Public address — your wallet address (starts with 0x...), which you can share with others to receive funds.

Important: MetaMask stores private keys only on your device, encrypted with your password.

How do transactions work?

When you send cryptocurrency or interact with a dApp:

• MetaMask creates a transaction with your data
• The transaction is signed with your private key (locally on the device)
• The signed transaction is sent to the blockchain network
• Miners/validators confirm the transaction
• Funds are transferred to another address

Connecting to dApps

One of the main functions of MetaMask is connecting to decentralized applications:

• Go to the dApp website (e.g., Uniswap or OpenSea)
• Click the "Connect Wallet" button on the site
• Select MetaMask from the list of available wallets
• Confirm the connection in the MetaMask window
• Now the site can request transactions from you (which you always confirm manually)

Networks and Switching Between Them

MetaMask is initially configured for the Ethereum network, but you can add other networks:

• Ethereum Mainnet — the main Ethereum network
• Polygon — fast and cheap network with EVM compatibility
• BNB Smart Chain — Binance exchange network
• Arbitrum, Optimism — L2 solutions for Ethereum

Switching between networks happens instantly via the dropdown menu in the wallet interface.

Gas and Fees

Any transaction in the blockchain requires a fee payment (gas):

• The fee size depends on network congestion
• In MetaMask you can choose transaction speed (slow, average, fast)
• For L2 networks (Arbitrum, Polygon) fees are hundreds of times lower than in Ethereum