Non-custodial (also called self-custody) describes a wallet or service where the user retains full control of their own private keys and, by extension, their cryptocurrency. No third party can access, freeze, or move the funds. Non-custodial wallets include hardware wallets, software wallets, and browser extensions. The trade-off is that the user is solely responsible for securing their keys and seed phrase. Losing them means permanent loss of access to the funds.