Why master password is required in Firefox or any other browser? Consider that you have set an alpha numeric password for your mailing account or for your social account,since you are always visiting those site constantly you will be saving those passwords in your web browser which automatically puts your username and password when you visit those sites.But what about the safety of your passwords that you have saved?Anyone who is little experienced can navigate to security>password section.This problem can be solved by setting a master password,which pops up when password field is required in security>password section. How To Set