what is most coommn appliction that use asp.net

[NOORSF]

hi,
i am beegner to learn asp.net so ineed any body help me :( .. pleeeeeeas:o
I need some information about asp.net:

-what is most coommn appliction that use it?
- i know it can use with oracle,sql,mysql...
but i need to knwow
what is best dbms we can use with it??

thankssssss ...