A linear function is one whose highest power is one (e.g y = mx +c) A non linear function is one that has powers greater than one (e.g quadratic equations (highest power = 2), cubic equations (highest power = 3), quartic equations (highest power =4))
A linear function has a constant rate of change, while a nonlinear function does not. For a table of values to be linear, the outputs must have a constant rate of change as the inputs increase by 1. On a graph, the function must be a straight line to be linear.