The short answer, what the code actually covers, and the honest distinction between real ASCII and the Unicode text most of the web calls "ASCII" today.
ASCII stands for American Standard Code for Information Interchange. It's a character-encoding standard that assigns a number from 0 to 127 to 128 characters — the English letters (upper and lower case), the ten digits, common punctuation, and a set of non-printing control codes. It's a 7-bit code, first standardized in 1963, and it became the common foundation for how computers represent text: its 128 characters are exactly the first 128 code points of Unicode, so any plain ASCII text is automatically valid Unicode text too.
The 128 ASCII codes split into three ranges:
See every printable code laid out with its decimal, hex, binary, and octal value in the full ASCII table, or convert whole words and sentences instantly with the ASCII converter.
ASCII predates the modern internet, yet it's still everywhere under the hood. Plain-text files, URLs, email headers, HTTP, programming language source code, and countless file formats all lean on ASCII as their safe, universally-understood baseline — a character that's plain ASCII will render correctly on essentially any system ever built, with zero risk of the missing-font "empty box" problem that can affect more exotic Unicode characters.
It also matters because of what came after it: Unicode was designed to be backward-compatible with ASCII rather than replace it outright. The result is that ASCII isn't a competing, legacy standard — it's the stable core that every modern text encoding, including the UTF-8 that powers most of the web, still agrees on.
This is the part worth getting right: ASCII and Unicode are not the same thing, and most of what gets casually called "ASCII" today is actually Unicode.
ASCII covers exactly 128 characters. Unicode covers well over 149,000, spanning nearly every writing system, symbol, and emoji in use. Unicode's first 128 code points are defined to be identical to ASCII — that's why the relationship is one-directional: every ASCII character is valid Unicode, but the vast majority of Unicode characters are not ASCII. Accented letters like é or ñ, box-drawing and block characters like ░ or █, symbols like ♥ or ★, and virtually all emoji sit well outside ASCII's 0–127 range.
That distinction matters in practice because so much of what people share and search for as "ASCII art" or "ASCII symbols" — dividers, borders, decorative text — is genuinely built from Unicode block and symbol characters, not the original 95 printable ASCII characters. Classic ASCII art (the kind that renders identically in any plain-text terminal from any era) sticks strictly to characters like / \ | - _ ( ) * . , and letters. If a piece of "ASCII" text depends on a modern font to render a glyph correctly, it's Unicode wearing ASCII's name.
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ASCII stands for American Standard Code for Information Interchange. It was developed in the early 1960s by the American Standards Association (ANSI's predecessor) as a common way for different computers and teletype equipment to represent the same text.
ASCII is a 7-bit character-encoding standard: a fixed table that maps the numbers 0 through 127 to 128 specific characters, so any device that agrees on the standard can turn those numbers into the same letters, digits, punctuation, and control codes. It is the common ancestor most modern text encodings, including Unicode, are built on top of.
No. ASCII defines only 128 characters (codes 0–127), while Unicode defines over 149,000 characters covering essentially every writing system, symbol set, and emoji in use today. They are compatible, not identical: Unicode's first 128 code points are defined to be exactly ASCII, so any valid ASCII text is also valid Unicode text. But the reverse isn't true — most Unicode characters, including accented letters, emoji, and the vast majority of what's shared online as "ASCII art" or "ASCII symbols," fall well outside the ASCII range and are not actually ASCII.
128. That's codes 0 through 31 (33 non-printing control codes), 32 through 126 (95 printable characters — letters, digits, punctuation, and the space), and 127 (the DEL control code).
Classic ASCII art is: it's built entirely from the 95 printable ASCII characters, like /, \, |, -, _, and letters, which is why it displays identically in any plain-text environment. A lot of what gets called "ASCII art" today actually uses Unicode block, box-drawing, or symbol characters (like ░, █, or ♥) that sit outside the ASCII range — it looks similar but depends on Unicode font support to render correctly.
Extended ASCII refers to various 8-bit encodings (codes 0–255) that kept the original 128 ASCII characters in place and used the extra 128 slots for accented letters, box-drawing characters, or symbols. There was never one official extended ASCII standard — different vendors and code pages (like Windows-1252 or Latin-1) assigned different characters to those upper codes, which caused compatibility problems that Unicode was designed to solve.