What is a binary digit (bit) characterized by?

A binary digit, commonly referred to as a bit, is fundamentally characterized as representing the on and off states of a computer's switches. In binary notation, which is the basis of digital computing, a bit can take one of two values: 0 or 1. These values correspond directly to the electrical states in a computer—0 typically indicates an off state, and 1 indicates an on state. This simple representation allows for the encoding of more complex data and operations, making it a crucial component of how computers process and store information.

In contrast to the other options, the focus here is on the basic operational role that a bit plays in the binary number system and computer architecture. The concept does not pertain to values less than zero, measurements of processing speed, or types of storage devices, providing a clear distinction for what defines a binary digit in the realm of computing.