4.1 Classical bits and logic gates

In classical computing, the smallest piece of information is called a bit. A bit may take only one of two logical values: either 0 or 1. Strings of bits are used to represent information as numbers, which can be stored, copied and processed by the computer. The processing of information is accomplished by logic gates, which take strings of bits as their input and produce an output value for each bit that they act on. A diagram showing how a logic gate works is given in Figure 4.

Figure 4 A diagram to illustrate how a logic gate works