A concept which varies is variable. These can be different in quantitative values. For example, weight, height, income are examples of variables. Qualitative phenomena are also qualified on the basis of the presence or absence of the attributes. Phenomena which can take on different values even in decimal points are called continuous variables. If these are explained or expressed in integer values these are discrete variables. Age is an example of continuous variable. Number of children is an example of discrete variable. If one variable is dependent on the consequence of another variable it is a dependent variable and variable which is antecedent to the dependent variable, it is termed as independent variable. For example height depends on age. Here height is dependent variable and age is independent variable.