Is secondary password (e.g. PIN) necessary?
I find some cases (especially in online games) that a software or website asks users to enter an additional password, such as 4 or 6 digit PIN, in addition to their original password. Most of the cases, the PIN is prompted immediately after users successfully log in with their username and password.
Is this really necessary?
Does an additional password make the site or software more secure?
In what scenarios is it needed to use an additional password?
But I mean by "PIN" is a secret code that has the same usage / behavior as a password.
The PIN is secret, can be changed by the user, and checked by the page/software like a password is.
Here's one example I encountered in an online game:
When a user runs the game for the first time, the game prompts to enter a PIN consisting of 4 digits. This PIN can be changed later.
The PIN is always used whenever the user logs in again, and is prompted after the user enters his/her username and password.
