Why is the Correlation Coefficient R squared and not just R?

R is used to determine whether the relationship is positive or negative based upon the sign of R. R^2 is the predictive percent of behavior in the output that can be explained by the input. R^2 <30% are considered to have no correlation and behavior is explained by chance R^2 of 30% to 49.99% are considered to be a mild relationsip R^2 of 50% to 69.99% are considered to be a moderate relationship R^2 of 70% to 100% are considered to be a strong relationship