The domain is the set of all possible x-values which will make the function "work", and will output real y-values.

Definition of Range :

The range of a function is the complete set of all possible resulting values of the dependent variable (y, usually), after we have substituted the domain.

In plain English, the definition means:

The range is the resulting y-values we get after substituting all the possible x-values.

Definition Of Independent Variable

Independent variable is a variable in an equation, whose values make up the domain.

In other words, an independent variable in an equation may have its value freely chosen regardless the values of any other variable.

Definition Of Dependent Variable

Dependent Variable is a variable whose value depends on the values of one or more independent variables.