Wallets hold keys, not coins
Your wallet doesn’t store coins. It stores private keys (or a seed phrase) that let you authorize moves on a blockchain. The ledger stays on the network; the wallet is your remote control for signing transactions against that ledger.
When you “send,” you’re broadcasting a signed message that tells the network to change ownership records. Lose the keys and you lose the ability to sign. Share the keys and you’ve effectively handed someone else your funds.
| Type | Pros | Cons | Use it for |
|---|---|---|---|
| Hot (software) | Convenient, fast | Online risk, phishing | Daily spend, small balances |
| Cold (hardware/air-gapped) | Keys stay offline | Less convenient | Savings, larger holds |
| Custodial | Password reset, easy UX | Counterparty risk | Short-term trading/fiat ramps |
Seeds, keys, and addresses
A seed phrase (typically 12–24 words) can deterministically generate all your private keys and addresses. Back it up offline; anyone who sees it can recreate your wallet. Private keys create signatures; public keys derive addresses. Addresses are what you share; seeds and private keys are what you protect.
“Not your keys, not your coins.” It’s cliché because it’s true.
Hot vs. cold
Hot wallets stay online (browser extensions, mobile apps). They’re convenient for daily use, trading, DeFi, NFTs, and payments—but exposed to malware, phishing, and bad signing prompts.
Cold wallets keep keys offline (hardware wallets, air-gapped devices, paper backups). You connect them only to sign, so attack surface shrinks. They’re slower but safer for long-term holdings.
Custodial vs. self-custody
Custodial: An exchange or app holds your keys. You get convenience, password resets, and sometimes compliance limits. You also take on counterparty risk: if they freeze accounts, get hacked, or go insolvent, your coins are stuck in their wallet, not yours.
Self-custody: You hold the keys. No help desk, no password reset, no “oops” button. You gain sovereignty and lose excuses—backups, secure devices, and careful signing habits are your responsibility.
Hardware wallets and signers
Hardware wallets isolate keys in a secure chip and display transaction details on a separate screen. You confirm with physical buttons, making it harder for a compromised laptop to trick you. Some setups pair a hardware signer with a mobile/desktop wallet that handles the UI while the device signs.
Multi-wallet setups
Use separate wallets for separate roles: a “spending” hot wallet with small amounts, a “vault” cold wallet for savings, maybe a dedicated wallet for NFTs or experiments. Compartmentalizing limits blast radius if one key set is compromised.
Backups and recovery
Write your seed phrase on paper or steel; store it offline and separated from your daily devices. Don’t screenshot or cloud-sync it. Test recovery with a small wallet so you know the process works before trusting larger sums. Consider Shamir splits or multisig for higher-stakes holdings.
What a good wallet should show you
Clear sender/receiver addresses, amounts, network fees, and what contract call you’re signing. On smart contract interactions, a readable summary (e.g., “Approve spend of 100 USDC for Uniswap router”) matters; “data: 0xabc123…” is not enough for safety.
“Most hacks are just bad clicks.”
Common mistakes
Reusing passwords for custodial accounts. Signing blind approvals. Keeping seed phrases in email or cloud notes. Plugging hardware wallets into random machines. Sending to the wrong chain (e.g., BTC to an ETH address). Recovery “helpers” who ask for your seed. If someone asks for your seed, they’re asking for your money.
When to use which wallet
Daily DeFi or frequent swaps: a reputable hot wallet paired with a hardware signer. Long-term holds: hardware or multisig with offline backups. Testing airdrops or unknown contracts: a throwaway wallet with nothing you can’t lose. Custodial: only for quick trades or fiat ramps, not as a savings vault.