This is how my key is set up:
pub 4096R/AAAAAAAA created: 2012-11-14 expires: 2013-11-14 usage: SC trust: ultimate validity: ultimate sub 4096R/BBBBBBBB created: 2012-11-14 expires: 2013-11-14 usage: E [ultimate] (1). xxxx <email@example.com>
I know this is standard, to have the subkey handle decryption. Why is this though? How is this different from me just having a single key that does everything?