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Op-amps and Transistors
An operational amplifier is a circuit that uses a number of basic components, including transistors. It is possible to build an op-amp from scratch -- this is sometimes assigned as an exercise in practical electronics -- but you typically encounter op-amps in the form of integrated circuits, or "chips."
Vcc and Vee
Vcc and Vee are used to denote the positive and negative, respectively, voltage supply in op-amp circuits and other electronic diagrams. They derive from the notation used on transistor circuit diagrams. A bipolar junction transistor (BJT) has three terminals: the collector, emitter and base. When analyzing certain configurations of a bipolar junction transistor, "Vc," "Ve" and "Vb" can be used to denote the voltages at the collector, emitter and base terminals, respectively. Resistors are typically associated with these terminals, and are labeled "Rc," "Re" and "Rb." The notation "Vcc," "Vee" and "Vbb" is then used to differentiate between the voltage at the terminal itself and the voltage beyond the resistor.
Alternative Notation
The simplest way to denote positive and negative terminals is to use "V+" and "V-"; however, this can cause confusion on an op-amp diagram, as "V+" and "V-" are sometimes used to denote the non-inverting and inverting inputs of the op-amp. Using "Vcc" and "Vee" makes it clear exactly what is being referred to. The negative voltage pin or terminal in a digital integrated circuit may also be labeled "GND."
Alternative Terminology
Field effect transistors (FETs) are a different kind of transistor. Instead of collector, emitter and base terminals, FETs have drain, source and gate terminals. In circuits using technology based on FETs instead of BJTs, the positive terminal may be labeled "Vss" instead of "Vcc," and the negative terminal "Vdd" instead of "Vee." You may see this form of notation in op-amps based on complementary metal-oxide semiconductor (CMOS) technology.