ASCII Table

ASCII is a 7-bit character set with exactly 128 code points (0-127), defined in 1963. It covers English letters, digits, basic punctuation, and 33 control characters. Unicode is a much larger system designed to encode every character of every writing system in the world (currently 150,000+ characters across 1.1 million possible code points). ASCII is a strict subset of Unicode, the first 128 Unicode code points (U+0000 to U+007F) are identical to ASCII. UTF-8 is the modern encoding of Unicode; for any ASCII character, the UTF-8 byte is identical to the ASCII byte, which is why UTF-8 is backwards-compatible with ASCII text files.

There is no single 'extended ASCII'. The term refers loosely to any of dozens of 8-bit character sets that extend the original 7-bit ASCII into the 128-255 range. The most common is ISO 8859-1 (Latin-1), which adds Western European accented characters, currency symbols, and some control codes. Windows-1252 is a slightly different superset used historically by Windows. Code page 437 was the original IBM PC extended ASCII, used for box-drawing characters in DOS. When you see corrupted characters in legacy text (mojibake), it is usually because two systems disagree on which 'extended ASCII' they were using.

ASCII codes 0-31 and 127 are control characters, they were originally telegraph and teletype commands, not printable glyphs. The ones still in active use: NUL (0) is the C-string terminator; TAB (9), LF (10), and CR (13) are whitespace; ESC (27) starts ANSI terminal escape sequences for colors and cursor movement; BEL (7) makes the terminal beep; DEL (127) is sent by the Backspace key on most modern keyboards (not BS / 8, despite the name). Ctrl-C produces ETX (3), Ctrl-D produces EOT (4), Ctrl-Z produces SUB (26), these are the basis of common terminal shortcuts.

ASCII 8 (BS) is the original Backspace from teletype terminals, it moved the print head one position to the left without erasing. ASCII 127 (DEL) was originally used to punch out an unwanted character on paper tape by setting all bits to 1 (which is why its value is 0x7F, all seven bits set). On modern keyboards, the Backspace key actually sends DEL (127), not BS (8), which surprises developers writing raw terminal code. In most shells and text editors, both end up doing the same thing (delete the character to the left), but the underlying byte differs.

ASCII was designed in 1963 around 7-bit bytes, the 8th bit was reserved for parity checking on telecommunications links. With 7 bits you get exactly 2^7 = 128 code points. When 8-bit bytes became standard in the 1970s and 1980s, vendors used the extra 128 slots for non-English characters (Latin-1, Cyrillic, Greek, etc.), but they all disagreed on which characters went where. This fragmentation drove the creation of Unicode in 1991, a single character set large enough to never need vendor-specific extensions again.

Every language has a built-in: JavaScript 'A'.charCodeAt(0) returns 65, Python ord('A') returns 65, Go []byte('A')[0] returns 65, Bash printf '%d' "'A" prints 65. For the reverse direction (code to character): JavaScript String.fromCharCode(65), Python chr(65), Go string(rune(65)), Bash printf '\%o' 65. For hex representations, JavaScript uses (65).toString(16) returning '41', Python hex(65) returning '0x41'. To convert a whole string at once, use the AllDevToolsHub ASCII Tool, it handles batch conversion and shows you every character's decimal, hex, binary, and HTML entity at a glance.