The identity element 
(also denoted 
,
, or 1) of a group
or related mathematical structure 
is the unique element such that 
for every element 
. In a group, the identity element is the group
element that leaves every group element unchanged under the group
operation. The symbol "
" derives from the German word for unity, "Einheit."
An identity element is also called a unit element.
Identity Element
See also
Binary Operator, Group, Group Element, Group Involution, Group Operation, Inverse Element, MonoidExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Identity Element." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/IdentityElement.html
