What happens when I type the wrong password?

Whenever I type the wrong password on my Ubu开发者_运维百科ntu/Gmail etc it takes some time to ask for password again. But if when I type the right password it immediately logs in.

Why? Is it because the algorithms's best case input is the correct password? Is it illusion then what causes it?

This is a common security measure, to prevent unauthorized users from trying a large number of strings to find your password. By making a short pause after an incorrect entry, it slightly incoveniences the user who enters the wrong password, but it greatly increases the protection from that sort of attack.

No, it's just to prevent someone malicious from trying multiple passwords quickly.

It has nothing to do with the algorithm.