If some quantity is growing linearly with time, then
-- its rate of growth is constant
and
-- its value is (a number) x (time).
A graph of its value against time is a rising straight line.
If the quantity is growing exponentially with time, then
-- its rate of growth is (a number) x (time)
and
-- its value is (time)^(a number)
A graph of its value against time is a rising curve.
