How crypto wallets work
What a wallet actually stores, how keys and addresses work, and why your seed phrase is the most important thing to protect.
A wallet doesn't hold your coins
This surprises most beginners: your crypto isn't stored inside your wallet. Coins and tokens exist only as records on the blockchain. What a wallet stores is the key that proves you control those records and lets you move them.
A better name for a crypto wallet would be a "keychain". If you lose the phone or app but still have your key, you can recover your funds in a different wallet. If someone else gets your key, they can move your funds, even if your phone is still in your pocket.
Public keys, private keys and addresses
Wallets use a technique called public-key cryptography. It works with a pair of mathematically linked keys:
- Private key: a very large secret number. It's used to "sign" transactions, which proves you authorized them. Anyone who has it controls the funds.
- Public key: calculated from the private key. It lets the network check your signatures without ever seeing your private key.
- Address: a shorter, shareable version of the public key, for example one starting with
bc1…on Bitcoin or0x…on Ethereum. It works like an account number you can give to others.
Getting the public key from the private key is easy, but working backwards is practically impossible. That's why you can share your address safely while keeping your private key secret.
The seed phrase (recovery phrase)
Most modern wallets don't show you a raw private key. Instead, they give you a seed phrase of usually 12 or 24 ordinary words, such as "orbit maple ladder…". All of your wallet's private keys are generated from this phrase.
That means your seed phrase is a master key to everything in the wallet. Anyone who has it can restore your wallet on their own device and take all your funds.
- Write it down on paper (or metal) and store it somewhere safe and private.
- Never type it into a website, never take a screenshot of it, and never store it in email or cloud notes.
- Never share it with anyone. No real support agent, exchange or wallet company will ever ask for it.
Types of wallets
Custodial vs. non-custodial
| Custodial | Non-custodial (self-custody) | |
|---|---|---|
| Who holds the keys? | A company, such as an exchange | You |
| If you forget your password | The company can usually help you get back in | Only your seed phrase can restore access |
| Main risk | The company could be hacked, freeze your account, or go out of business | Losing your seed phrase, or having it stolen |
People often say "not your keys, not your coins". With a custodial service, you're trusting a company to give your funds back when you ask.
Hot vs. cold wallets
- Hot wallets are apps or browser extensions connected to the internet. They're convenient for everyday use, but more exposed to malware and phishing.
- Cold wallets, usually small hardware devices, keep the private keys offline. Transactions are signed on the device itself, so the keys never touch your computer. They're better suited to larger amounts held for a long time.
Good habits for beginners
- Start small. Send a small test amount before moving anything significant.
- Check addresses carefully. Compare the first and last several characters. Some malware swaps copied addresses.
- Download wallets only from official sources. Fake wallet apps exist in app stores and search ads.
- Buy hardware wallets directly from the manufacturer. Never use one that arrives with a seed phrase already written down.
- Plan for the unexpected. Think about how a trusted person could access your funds if something happened to you.
- Wallets store keys, not coins. Your funds live on the blockchain.
- Your address is safe to share. Your private key and seed phrase are not.
- Whoever has the seed phrase controls the wallet.
- Custodial wallets trade control for convenience. Cold wallets trade convenience for security.
Check your understanding
1. Your phone with your wallet app breaks. Are your funds gone?
Not if you have your seed phrase. Your funds are on the blockchain, so you can restore the wallet on a new device using the phrase.
2. Which is safe to share publicly: your address or your seed phrase?
Only your address. Your seed phrase gives full control of your wallet and should never be shared.
3. A "support agent" on social media asks for your seed phrase to fix a problem. What should you do?
Refuse and block them. It's a scam. Real support teams never ask for seed phrases or private keys.
Keep learning
Educational content only. This lesson explains how a technology works. It isn't financial, investment or legal advice, and it doesn't recommend any wallet product. Always do your own research.