hexadecimals

Hexadecimal, often shortened to hex, is a base-16 numeral system used in mathematics and computer science. It uses sixteen distinct symbols: the digits 0 through 9 and the letters A through F (case-insensitive) to represent values zero to fifteen.

Because each hex digit corresponds to four binary bits (a nibble), hex provides a compact way to express binary data. A byte (eight bits) is typically written as two hex digits, and larger values are built by grouping hex digits. For example, the 16-bit value 0x1A3F equals decimal 6719.

Hex literals appear in various notations. Many programming languages denote hex values with a 0x prefix (0x1A3F). Some assembly languages use a trailing h (1A3Fh). In web development, color values in CSS and HTML are written as hex triplets or six-digit codes, beginning with a hash sign, such as #FF0000 for red.

Common uses include representing memory addresses and machine code, encoding binary data in a human-readable form, and specifying colors in graphics and web design. Hex is also used in debugging and data dumps, where bytes are shown as pairs of hex digits. Unicode code points and other binary formats are frequently expressed in hex as a convenient shorthand.

While hex is a standard tool in computing, it is not a positional system in everyday arithmetic. Its name derives from the Greek for sixteen and the Latin for decimal, reflecting its role as a convenient bridge between binary and decimal representations.