When you select Google or Facebook to sign up/login for an inzpire.me account, you are electing to use your Google or Facebook username and password to sign up/login. This is a login service offered by Google and Facebook, and the service assists in making your logins safer by allowing you to log into different websites with one password. This means that you won't have to remember your email and password for each account that you have.
It also offers the convenience of changing your password (as often as you'd like!) on one channel rather than multiple channels.
Please note that inzpire.me does not receive any of your personal information or data from Google or Facebook. Opting to sign up/login to inzpire.me using this login service does not grant us access to any of your information.