A word-based wallet recovery backup, often using BIP-39; successful restoration can also require a passphrase, derivation paths, and the correct wallet format.

Control of the keys or authorization policy needed to use an on-chain account, with responsibility for protecting and recovering that authority.

A 256-bit hash function from the SHA-2 family. Bitcoin uses it for proof of work and address hashing.

Code deployed on a blockchain that executes deterministically when called.

A tighter rule set that old nodes still see as valid, so the network can upgrade without a clean split.

Creating many fake identities to outvote honest peers. Proof of work and stake make this expensive.

Making it expensive to fake many users, via stake, identity, or proof of personhood.