Rainbow Table
Rainbow tables are lists of precomputed values that can be used to more quickly break a password. Since the values don’t have to be calculated for each password being guessed, this can save a lot of time.
Warning!
There are a few ways to avoid rainbow tables. One is to use a hashing algorithm that is designed to be resistant to them, such as bcrypt. Another is to use a salt, which is a random string of data that is added to the input of a hashing function to make it harder to precompute values for a rainbow table.