When r = 1 , the correlation is perfect positive. In this case, proportional change in two variables is linear and is in the same direction.
When r = -1 , the correlation is perfect negative. In this case , proportional change in two variables is linear and is in the opposite direction.
When r =0 , the two variables are uncorrelsted. There is no linear relationship between them. However, it does not imply that the two variables are independent.
