Variables can be broadly categorized into two types: quantitative and qualitative.

Quantitative variables are measured on a numeric scale, allowing for mathematical operations like addition, subtraction, multiplication, and division.
Qualitative variables, sometimes called categorical variables, represent categories or groups that cannot be reduced in meaning to numerical values. 

Watch out!!: Categories are frequently represented using numbers (e.g., see codebook).

Hint: We can only do mathematical operations with quantitative variables.