Crypto Wallets Explained

What a wallet actually stores

Despite the name, a crypto wallet does not hold coins the way a physical wallet holds cash. Your cryptocurrency exists as a record on the blockchain. What the wallet holds is your private key — the secret that proves you own a particular blockchain address and authorises you to move the funds there.

This distinction matters: if your wallet app is destroyed, the funds are not gone, because the blockchain still records your balance. What would be gone is your ability to access those funds, unless you have a backup of your private key (usually stored as a seed phrase).

Private keys, public keys and addresses

These three things are related but different:

• Private key — a long secret number known only to you. It signs transactions to prove authorisation. Never share it.
• Public key — derived mathematically from the private key. You can share it freely.
• Address — derived from the public key and shortened into a human-usable string (e.g. 1A1zP1...). This is what you give to someone who wants to send you crypto.

The relationship is one-way: you can derive a public key from a private key, and an address from a public key, but you cannot reverse either step. Sharing your address is safe. Sharing your private key gives someone complete control of everything in that wallet.

Hot wallets vs cold wallets

Hot wallets are connected to the internet. This includes exchange accounts, browser extension wallets (like MetaMask) and mobile apps. They are convenient for frequent transactions but exposed to online attack — malware, phishing and exchange hacks.

Cold wallets keep keys offline. Hardware wallets are dedicated devices that sign transactions without ever exposing the key to a networked computer. Paper wallets (a printed key) are another form, though more fragile. Cold storage trades convenience for security, making it suited to funds you do not move often.

The practical rule of thumb: keep what you actively spend in a hot wallet, and move long-term savings to cold storage.

Custodial vs self-custody

Custodial means a third party — usually a centralised exchange — holds the private keys on your behalf. You log in with a password and trust them to keep the keys secure. If the exchange is hacked or collapses, your ability to recover funds depends entirely on the company. Several large exchanges have collapsed and customers have lost funds.

Self-custody means you control the private key yourself. No company can freeze your account or block a withdrawal. The trade-off is that you are entirely responsible for your own security: lose the key, and there is no support line. Make a security mistake, and there is no chargeback.

Neither option is strictly better; it depends on the amount held, how often you transact, and your personal security practices. Many people use custodial accounts for convenience and self-custody for larger long-term holdings.

Seed phrases

When you create a self-custody wallet, it generates a seed phrase (also called a recovery phrase or mnemonic) — a list of 12 or 24 ordinary words. These words encode your private key in a form that is human-readable and can be used to restore your wallet on any compatible device.

The seed phrase is the most critical thing to protect. Rules:

• Write it down on paper and store it somewhere physically secure.
• Never type it into a website or app. No legitimate wallet will ever ask for it after setup.
• Never photograph it or save it in cloud storage — phones and cloud accounts are compromised regularly.
• Consider keeping copies in two different physical locations in case of fire or flood.

The most common ways people lose crypto

• Phishing — a fake website or message tricks you into entering your seed phrase or approving a malicious transaction.
• Exchange collapse or hack — a custodial platform fails and user funds are unrecoverable.
• Lost seed phrase — the backup was not made or cannot be found; self-custody funds are permanently inaccessible.
• Malicious app approval — signing a smart-contract interaction that grants an attacker unlimited access to your tokens.
• Sending to the wrong address — crypto transactions are irreversible; always double-check the recipient address before confirming.

Related glossary terms

• Private key
• Cold wallet
• Seed phrase
• Custodial

Educational content only. Not financial advice. Security practices depend on your specific situation. Do your own research before deciding how to store your assets.