Adding Salt to Hashing: A Better Way to Store Passwords

A salt is added to the hashing process to force their uniqueness, increase their complexity without increasing user
requirements, and to mitigate password attacks like rainbow tables

Detailed can refer to the following link

https://auth0.com/blog/adding-salt-to-hashing-a-better-way-to-store-passwords/

Summary

• A cryptographic salt is made up of random bits added to each password instance before its hashing.
• Salts create unique passwords even in the instance of two users choosing the same passwords.
• Salts help us mitigate rainbow table attacks by forcing attackers to re-compute them using the salts.
• Creating cryptographically strong random data to use as salts is very complex and it’s a job better left to leading
  security solutions and providers.