A non-custodial wallet is a software or hardware tool that lets its user control the private keys used to authorize transactions. Unlike a custodial exchange account, it does not rely on a service provider to hold and manage those keys. Whoever controls the keys can generally move the associated crypto-assets.
This matters in cybersecurity because key security becomes the user’s responsibility: malware, phishing, device theft, or loss of a recovery phrase can lead to irreversible loss. In criminal investigations, a wallet controlled directly by a person may be harder to secure than assets held by a platform, which can sometimes restrict account activity. Defenders should protect keys and recovery phrases, while investigators must distinguish control of a wallet from merely identifying its blockchain address.