A variable is any entity that can take different values. The types of variables are :
Dependent variables : The dependent variable is characterized as a variable whose state quality depends on the estimation of another variable.
Independent variables : Independent variables represent variables whose values do not depend on change.
Control variables : The values of these variables are affected by the change in independent variables.
Random variables : Random variables are mathematical forms of quantities or objects that depend on random events.
Categorical variables : A categorical variable (also known as a qualitative variable) is a variable that can take one of a limited number of normally fixed numbers of possible values.