Domain of a function. is the set of all possible input values for. which the given function. is defined. The function provides. an output for all the possible values. of a domain. . Functions is a very important topic mathematics. These are relation which give set of output corresponding to a set of inputs. While dealing with functions, students come across the two very handy concepts domain and range quite frequently Domain of a function is defined as the group of all x values or all inputs. These input values when applied to the function, must produce corresponding output values. In other words, the domain of a function is the set of all the values or numbers that go inside the function to provide outputs. The range of a function is supposed to be the collection of all possible outputs or values of y. The range is also denoted by f (x); where x is the independent variable in function f. Thus, domain and range are two different operations performed on a set of values and the given function. Briefly, the domain of a function is the set of all possible input values whereas the range is the set of all possible output values. On the graph of a function, the set of values towards the direction of the X axis is the domain ; while, the set of values towards the direction of the axis is termed as range. The range is also called as codomain. The domain of a function: All possible input values. The range of the function: All possible output values.