For functions in context, the input is often referred to as the
independent variable because it can be chosen arbitrarily from the domain. Conversely, the output is called the
dependent variable, because its value depends on the value of the independent variable. For example, consider how the cost of fruit is determined by weight.
If the unit price of clementines is then the total cost of buying clementines depends on how many pounds are bought. Therefore, the cost of clementines is the dependent variable and the number of pounds is the independent variable.