ASCII 95 — _

The underscore (low line) is crucial in programming, appearing in variable names, function names, and identifiers across virtually every language. In Python, single leading underscores mark private members by convention, double underscores trigger name mangling for class internals, and standalone '_' captures unused values or last REPL results. In JavaScript, the Lodash utility library uses '_' as its namespace. In file systems, underscores substitute for spaces in filenames to avoid escaping issues. The underscore is the only punctuation character universally allowed in programming identifiers.

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, Underscore is assigned code point 95 in decimal (0x5F hexadecimal, 137 octal, 01011111 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 Underscore works reliably across all operating systems, programming languages, and internet protocols.