Why is r preferred to covariance as a measure of association?

Although correlation coefficient is similar to the covariance in a manner that both measure the degree of linear relationship between two variables, but the former is generally preferred to covariance due to the following reasons.

1. The value of the correlation coefficient (r) lies between 0 and 1. Symbolically –1 ≤ r ≤ +1

2. The correlation coefficient is scale free.