vcc, vbb?

[adgators89]

I saw these on some schematics and was wondering what they were

[pjwhite]

Vdd, Vss, Vgg, Vcc, Vbb, Vee, etc. usually refer to common power supply voltages, oriented towards various transistor elements in a circuit.  In CMOS digital circuits, you will commonly see Vdd = +5 volts, Vss = 0 volts (ground).  The "dd" and "ss" refers to MOSFET drain and source, respectively.  The transistor drain goes towards the +5 volt supply while the source goes towards ground.  I don't see many Vgg references anymore, but they exist.  Likewise in bipolar transistor circuits, you will see Vee (emitter) Vcc (collector) and Vbb (base) voltages.
Tube circuits will use Vpp (plate), as will some transistor circuits with high positive voltage requirements.