Based on the nature of the relationship between the two variables, correlation can be broadly classified into the following three categories: Positive and Negative Correlation, Linear and Curvilinear Correlation, and Simple and Multiple Correlations
The study of relationships among three or more than three variables simultaneously is called multiple correlations. For example, the study of the relationship between price, demand, tastes, and income of the consumers.
Also, Read Positive and Negative Correlation