What is the base-2 number system that utilizes only 0 and 1?

The binary system is a base-2 number system that consists exclusively of the digits 0 and 1. This system is fundamental to computer science and digital electronics because it aligns perfectly with the binary nature of electronic circuits, which can be in an 'on' (1) or 'off' (0) state.

In essence, each digit in a binary number represents a power of 2, allowing for the representation of any integer using just these two digits. For instance, the binary representation '101' corresponds to the decimal number 5 (1x2^2 + 0x2^1 + 1x2^0).

In contrast, the hexadecimal system uses sixteen different symbols (0-9 and A-F), and the decimal system employs ten symbols (0-9). Structured data refers to organized information that can be easily searchable in databases but does not relate to number systems in the same way as binary, decimal, or hexadecimal. Thus, the binary system is uniquely characterized by its use of only the numbers 0 and 1, confirming it as the correct choice.