The *domain* is the set of values on which a function operates. For instance, the domain of the square root function is usually taken to be the non-negative real numbers, while the domain of the function \(f(x)=\dfrac{1}{x}\) is usually taken to be all real numbers except for \(0\).

We can also specify different domains for these functions, such as defining a function \(g(x)=\dfrac{1}{x}\) on all positive real numbers, or on all real numbers between \(2\) and \(10\), or on all non-zero integers.