A PIN code is a "one time password". It allows you to create a new personal password for your account. You need it for example if you want to log in TUMonline the first time or if have forgotten your password.
Students can obtain a PIN code from from IT-Support or click on "login" at the TUMonline homepage and then on "Forgot your password?":
Screenshot: Password forgotten
You can redeem the PIN code in TUMonline. Click on "login" in the upper right corner:
Screenshot: Login link in TUMonline
The log-in page then appears. You can enter your PIN code in the center of the page, differentiated according to students, staff and alumni:
Screenshot: redeeming PIN code
Click "Save" after correct entry of the data. After that you can define a new password for your account.