Help chapters:
Frequently Asked Questions (FAQ):
An OpenID is a unique identifier that allows you to log on to websites that implement an OpenID login. You do not need to create a new account locally, but can log in using your existing login credentials - like for example your Google account. It is entirely safe, as you are redirected to the corresponding website to log in (e. g. Google), so your login credentials do not need to be specified on the originating website.
These tools use an OpenID for two reasons: simplicity and security.
There are many OpenID providers, the most well known are Google, Facebook or Yahoo to name a few. You can find a comprehensive list as well as more information on the official OpenID website:
A few examples of OpenIDs: