rainbow-table-attack
Definition
A rainbow table attack is a password-cracking method that uses a special table (a “rainbow table”) to crack the password hashes in a database.
How it works
Applications don’t store passwords in plaintext, but instead encrypt passwords using hashes. After the user enters their password to login, it is converted to hashes, and the result is compared with the stored hashes on the server to look for a match. If they match, the user is authenticated and able to log in.
More on source