Seed Phrase
A human-readable list of usually 12 or 24 words that backs up and can fully restore a crypto wallet's private keys.
Definition
A seed phrase is a mnemonic representation of the master secret behind a non-custodial wallet's keys. Anyone who has the phrase can recreate the wallet and take all its funds, and if the phrase is lost the funds are typically gone forever, with no password reset. Best practice is to record it offline, never type it into websites, and never share it. Seed-phrase theft via phishing, fake apps or malware is a leading cause of irreversible crypto loss, a risk that is especially relevant when interacting with unregulated gambling sites and their promotions.
Worked example
Setting up a hardware wallet, you write 24 words on paper and store them offline; if the device breaks, entering those words into a new device restores your funds.
Why it matters
The single most important self-custody security concept; losing or leaking it means losing funds, and it is a frequent target of scams around gambling sites.