1. Missing Completely at Random: 

    - No systematic relationship between a column's missing values and 

    other or own values. 

    - eg : errors when inputting data

2. Missing at Random: 

    - There is a systematic relationship between a 

    column's missing values and other observed values.

    - eg : missing ozone data for high temperature

3. Missing not at Random: 

    - There is a systematic relationship between a 

    column's missing values and unobserved values.

    - eg : missing temperature values for high temperature

print(df.isnull().sum())