ASCII 58 — :

The colon introduces lists, explanations, and quotations in English prose. In programming, colons appear in Python's block-defining syntax ('if x:'), JavaScript and TypeScript object literals ('{key: value}'), CSS property declarations ('color: red'), and URL scheme separators ('https://'). In Unix systems, colons separate directory entries in the PATH environment variable. In IPv6 addresses, colons separate 16-bit address groups. The double colon '::' carries special meaning in C++ for scope resolution and in IPv6 for consecutive zero group compression.

Punctuation marks serve as the structural scaffolding of written language, delineating sentences, clauses, and phrases while conveying emphasis and grouping. In programming, these same characters gain powerful additional roles as operators, statement terminators, delimiters, and syntactic markers that compilers and interpreters rely upon. This dual significance in both natural language and code syntax means punctuation characters carry outsized functional importance relative to their small count in the ASCII character set.

In the ASCII encoding table, Colon is assigned code point 58 in decimal (0x3A hexadecimal, 072 octal, 00111010 binary). The 7-bit ASCII standard, first published in 1963 by the American Standards Association, defines exactly 128 characters that remain the foundation of text encoding systems worldwide. UTF-8, the dominant encoding on the modern web, is fully backward compatible with ASCII — every ASCII character is encoded as the identical single byte in UTF-8, guaranteeing that Colon works reliably across all operating systems, programming languages, and internet protocols.