Definition:Equals

Definition
The symbol $=$ means equals.


 * $x = y$ means $x$ is the same object as $y$, and is read $x$ equals $y$, or $x$ is equal to $y$.


 * $x \ne y$ means $x$ is not the same object as $y$, and is read $x$ is not equal to $y$.

The expression:
 * $a = b$

means:
 * $a$ and $b$ are names for the same object.

Equality
The word equality is the noun derived from the verb equals.

Also see

 * Equals is an Equivalence Relation

Historical Note
The equals sign was introduced by Robert Recorde in his 1557 work:
 * The Whetstone of Witte, whiche is the seconde parte of Arithmeteke: containing the extraction of rootes; the cossike practise, with the rule of equation; and the workes of Surde Nombers.

Placing two hyphens together, one above the other, he wrote:
 * "To avoide the tediouse repetition of these woordes: is equalle to: I will sette as I doe often in woorke use, a paire of paralleles, or gemowe lines of one lengthe: $= \!\!\! = \!\!\! = \!\!\! = \!\!\! =$, bicause noe .2. thynges, can be moare equalle."

The word gemowe comes from the Latin geminus meaning twin.