During data analysis, how will you treat missing values?

To identify the missing values the criteria is to find the variables with the missing values. Suppose a pattern is identified. Concentrating on it could give you interesting and meaningful observations. However, if in case no patterns are identified, we can replace the missing values with mean or median values or we can simply ignore them.

If the variable is categorical, we assigned the default value to the mean, minimum, and maximum. The missing value is then assigned to that default value.
If for a variable, 80% of the values are missing, then instead of treating the missing values we would drop that variable.