Password Locks allow you to prevent users from typing the passwords associated to specific sites into forms on sites that they do not belong to (ex. phishing pages).

For instance, you may want to add "login.microsoftonline.com" or "accounts.google.com" to prevent phishing email breaches.

If you're having issues with a Password Lock matching subdomains, make sure you type the Fully Qualified Domain Name 
(ex. www.LogonSafe.com - NOT logonsafe.com) to make it match correctly.