A numerical base, also known as a radix, is the number of unique digits, including zero, that a numeral system uses to represent numbers. For example, the decimal system, which is base 10, uses the digits 0 through 9. In contrast, the binary system, or base 2, uses only the digits 0 and 1. Each base determines how numbers are expressed and calculated. Different bases are used in various applications. The hexadecimal system, or base 16, is commonly used in computer science because it can represent large binary numbers more compactly. Understanding numerical bases is essential for fields like mathematics, computer programming, and digital electronics.