hashing

Question 1

hash

Answer 1

Hashing is the name given to a process in which an input (called a key) is turned into a fixed size value (called a hash). There are a vast number of algorithms, called ​hash functions​, which do this.

Question 2

can the output of a hash function be reversed?

Answer 2

no!
the output of a hash function​ can’t be reversed​ to form the key. This quality makes hashing useful for storing passwords. A password entered by a user can be hashed and checked against the key to see if it is correct, but
a successful hacker would only gain access to the keys, which​ can’t be reversed ​to gain the passwords.