The equals sign with a slash through it (≠): used in mathematics since at least Euler's era, the source of a whole family of negated-relation symbols, and left out of ASCII, which is why code uses != instead. Click any symbol to copy it instantly.
The not equal sign (≠, U+2260) combines the equals sign with a diagonal slash: Unicode's own decomposition shows it as literally “=” plus a combining slash overlay (U+0338), the same mark that produces a whole family of negated relations: ≁, ≉, ≢, ≮, ≯. The slash-negation convention is a distinct, later story from Robert Recorde's 1557 invention of “=” itself: the earliest known written use traces to Leonhard Euler's 18th-century correspondence, though historians of mathematics are careful to say the symbol was used by Euler, not necessarily invented by him. Because ASCII never allocated a slot for ≠, programming languages substituted their own stand-ins (!= in C-family languages, <> in SQL and Pascal, ~= in Lua and MATLAB, /= in Fortran and Haskell) which is why the math symbol and the code you actually type are almost never the same character.
The math symbol, and the ASCII stand-ins different programming languages adopted since ≠ itself was never part of the character set.
≠ isn't alone: the same diagonal-slash overlay negates several other relation symbols in Unicode's Mathematical Operators block.
A Discord nickname stops at 32 characters, an Instagram bio at 150, a TikTok bio at 80, and X weights some characters as two. The UltraTextGen counter reads all of them at once, and counts a multi-codepoint Unicode emoji the way each platform actually bills it.
Open the character counter →Operators, set notation, and mathematical constants in one browsable reference.
The comparison symbols ≠ sits alongside, and why they can break HTML.
Another math relation symbol pulled out of the math-symbols library for its own page.
The ≅ that every geometry class uses for congruent shapes: same shape, same size.
The ≤ you reach for when a value can be smaller than another value or exactly equal to it.