51 percent attack

The ability of someone controlling a majority of network hash rate to revise transaction history and prevent new transactions from confirming.

Address

A 20-byte hash formatted using base58check to produce either a P2PKH or P2SH Hellar address. Currently the most common way users exchange payment information.

Base58

The method used in Hellar for converting 160-bit hashes into P2PKH and P2SH addresses. Also used in other parts of Hellar, such as encoding private keys for backup in WIP format. Not the same as other base58 implementations.

Base58check

The method used in Hellar for converting 160-bit hashes into P2PKH and P2SH addresses. Also used in other parts of Hellar, such as encoding private keys for backup in WIP format. Not the same as other base58 implementations.

BIP32

The Hierarchical Deterministic (HD) key creation and transfer protocol (BIP32), which allows creating child keys from parent keys in a hierarchy. Wallets using the HD protocol are called HD wallets.

BIP70 payment protocol

The protocol defined in BIP70 (and other BIPs) which lets spenders get signed payment details from receivers.

Block

One or more transactions prefaced by a block header and protected by proof of work. Blocks are the data stored on the block chain.

Block chain

A chain of blocks with each block referencing the block that preceded it. The most-difficult-to-recreate chain is the best block chain.

Block header

An 80-byte header belonging to a single block which is hashed repeatedly to create proof of work.

Block height

The number of blocks preceding a particular block on a block chain. For example, the genesis block has a height of zero because zero block preceded it.