Not Sign ¬

The Not Sign character (¬) is a standard HTML entity defined in the HTML specification. In HTML source code, it can be written using the named entity reference ¬, the decimal numeric character reference ¬, or the hexadecimal numeric reference ¬. The character is assigned Unicode code point U+00AC in the Universal Character Set.

The not sign (¬) represents logical negation in mathematical logic and Boolean algebra. It inverts the truth value of a proposition. The symbol is also used in some programming languages and command-line interfaces. It is distinct from the tilde (~) and exclamation mark (!), which serve as negation operators in different contexts.

Symbol entities encompass a wide variety of special characters used in legal disclaimers, intellectual property notices, typographic ornaments, card suit indicators, and miscellaneous notation throughout web content. These characters appear in website footers for copyright notices, product pages for trademark symbols, academic papers for dagger footnote markers, and decorative or gaming contexts for card suits and stars.

When deciding how to encode the Not Sign character in your HTML documents, the named entity ¬ is generally the most readable choice for developers reviewing or maintaining source code. The decimal form ¬ and hexadecimal form ¬ are equally valid alternatives that work in contexts where named entities may not be supported, or when generating HTML output programmatically from server-side code. All three representations produce identical visual output in every modern web browser.

Use the not sign in formal logic expressions (¬P means 'not P'), truth tables, digital circuit descriptions, and mathematical notation. It represents the same concept as the ! operator in many programming languages but uses the standard mathematical notation for formal contexts.