Infinity

It means without a finite end or boundary. In a formula, ∞ marks an unbounded quantity, process or direction, such as a value growing without stopping. It is not an ordinary number you can count up to.

The idea is far older than the glyph. Ancient Greek thinkers argued about endless division and limitless space, and about whether infinity could ever be complete or could only keep going.

The sign itself first appears in 1655, in English mathematician John Wallis's treatise on conic sections (curves such as ellipses and parabolas). He used it for a curve that can be traced endlessly. The name lemniscate, sometimes given to the shape, comes from a later figure-eight curve.

Why does ∞ also mean forever?

Outside maths, it reads as an open-ended promise. The loop easily shifts from unbounded quantity to lasting love, loyalty, memory or personal continuity.

That is a later cultural reading, not the sign's original job. A plain ∞ stays broad; a heart makes it romantic, while a name or date makes the dedication specific. The surrounding message does more of the work than the glyph.