Whilst we have many fields on our profile pages, we don't force our users to fill them all. The fact is, that you don't have to write anything about yourself and still use our page and services.
We store all information about our users in our SQL database (PostgreSQL), the tables are stored on our hard discs.
Most of the profile fields are shown next to photos you uploaded for everyone to view, none of the fields is strictly private or confidential. Examples of the fields are: Cameras you own, your webpage, ... The info is shown in XHTML format and can be printed out.