Security

What is two-factor authentication?
How does two-factor authentication work?
What ways can be used for authentication?
Do I have to activate the two-factor authentication?
Can I deactivate two-factor authentication?
Is there a specific limit at which two-factor authentication is triggered?
I have not received my PIN code for two-factor authentication. What should I do?
I've received a PIN code but I did not request one. What can I do?
How can I change my password?
I have received an email that my password has been changed. What should I do?
I have received an email that my email address has been changed. What should I do?
I have received an email to confirm the change of my email address. What should I do?
I have received an email about an unexpected login. What should I do?