Correlation - is a statistical measure to quantify the strength of the relationship between two quantitative and continuous variables. The relationship can be one of the following
Positive - increasing one variable would increase the other
Negative - increasing one variable would decrease the other
No Correlation - increasing one variable has no impact on the other
Correlation is usually denoted by Pearson's Correlation Coefficient (r) and it ranges from -1 to 1.
-1: Perfect negative correlation
0: No correlation
1: Perfect positive correlation
An application oriented question on the topic along with responses can be seen below. The best answer was provided by Venugopal R on 11th October 2017.