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Two short horizontal parallel lines (=), denoting that the values on either side are equal.
Also known as: Equal sign
Introduced by Welsh mathematician Robert Recorde in his 1557 book The Whetstone of Witte, the equals sign is one of the most widely used symbols in mathematics, and has since also become a broader cultural symbol of equality and fairness.
Denotes that the mathematical expressions on either side have the same value; introduced by Robert Recorde in The Whetstone of Witte (1557), who explained his choice of two parallel lines 'bicause noe 2 thynges can be moare equalle'.
Wales / England · 1557 onward · Contexts: Mathematics
Used outside mathematics as a general symbol of equality or fairness, including in some social-justice and civil-rights campaign branding.
Specific campaign usages are their own distinct marks; this entry covers the general symbol only, not any single organisation's logo.
Contexts: Political movements
Is distinguished from the congruence sign by one bar. Three stacked bars mark a congruence — a statement relative to a modulus written in brackets at the end of the line — rather than an equality, and at small sizes the extra bar and the bracketed modulus are both easy to miss.
Contexts: Mathematics
Two short horizontal lines of equal length, stacked one above the other.
Two bars is equality; three is congruence, which depends on a modulus.
One equals sign assigns, two compare with type conversion, three compare without. The count of strokes is the whole of the difference.
Drawn identically; only whether atoms or quantities sit either side distinguishes a chemical bond from an equality.
The mathematical equals sign asserts equality; the same two strokes in a circle on a licensed work forbid distributing modified versions.