# Hash

A * hash function* is any function that can be used to map data of arbitrary size to fixed-size values. The values returned by a hash function are called hash values, hash codes, digests, or simply hashes. Use of a hash function to index a hash table is called hashing or scatter storage addressing. Like all computer data, hashes are large numbers, and are usually written as hexadecimal.

## Hash functions in JaxNet

### Mining hash functions

Jax.Network uses SHA-256d as a mining hash function. The letter 'd' refers to the fact that cryptographic hash function *SHA-256* is applied twice.

### Linking hash functions

*Linking hash function* is used to link data records in JaxNet in order to make them immutable. By design, this cryptographic hash function should be efficient and very fast.

Jax.Network uses Blake-256 as a linking hash function.