Crypto Wallet
A crypto wallet is a tool — software, hardware, or even a piece of paper — that stores the cryptographic keys allowing a user to access, send, and receive cryptocurrency on a blockchain.
Despite the name, a crypto wallet does not actually store cryptocurrency. The tokens themselves exist only as entries on the blockchain. What the wallet stores are the private keys — long cryptographic strings that prove ownership of a blockchain address and authorize transactions. Possession of the private key is possession of the assets; anyone with access to your private key can transfer your crypto without your consent.
Wallets are categorized along two dimensions: custodial versus non-custodial, and hot versus cold. A custodial wallet is one where a third party (such as a centralized exchange like Coinbase or Kraken) holds your private keys on your behalf. This is convenient — the exchange handles security and recovery — but it means you are trusting the platform with your assets. The collapse of FTX in 2022, which froze billions in customer funds, illustrated the counterparty risk inherent in custodial arrangements. The crypto community's response is often summarized as: not your keys, not your coins.
A non-custodial wallet stores keys under the user's sole control. Software non-custodial wallets (MetaMask, Phantom, Trust Wallet) run as browser extensions or mobile apps and remain connected to the internet — these are called hot wallets. Their convenience comes at the cost of exposure to online threats such as phishing, malware, and browser exploits.
Hardware wallets (Ledger, Trezor, Coldcard) are physical devices that keep private keys in an offline, air-gapped environment — these are called cold wallets. Signing a transaction on a hardware wallet requires physical confirmation on the device, meaning a remote attacker who has compromised your computer cannot authorize a transfer without also having the hardware device. For significant crypto holdings, hardware wallets are generally considered the security standard.
Seed phrases (also called recovery phrases or mnemonic phrases) are the 12- or 24-word strings that can regenerate a wallet's private keys if the device is lost or damaged. Protecting the seed phrase — storing it offline in a physically secure location, never entering it into any website or app — is the single most important operational security practice for any self-custody crypto holder.