Domain

Domain

The set of values of the independent variable(s) for which a function or relation is defined. Typically, this is the set of x-values that give rise to real y-values.

Note: Usually domain means domain of definition, but sometimes domain refers to a restricted domain.

Table showing 4 functions with their domains: x²−2x+5:(-∞,∞); (x+4)/(x−2): (-∞,2)∪(2,∞); √(x+5): [-5,∞); log(x−7): (7,∞)

Ellipse on xy-plane with points (-1,1), (5,1), (2,3), (2,-1) labeled. Domain is [-1,5]; x-values run from -1 to 5.