Is Arduino serial on TTL level?

I would like to know if Arduino works with TTL level serial data or not? Also, how about if I use other pins than the standard serial pins, for example with the softserial library?

Thanks in advance!

I would like to know if Arduino works with TTL level serial data

yes.

how about if I use other pins than the standard serial pins, for example with the softserial library?

SoftwareSerial operates at TTL levels as well.

-j

Thank you very much for your reply!