Mortgage insurance is required whenever the down payment amount is less than 20%. Mortgage insurance is an insurance policy that protects a mortgage lender or titleholder if the borrower defaults on payments, passes away, or is otherwise unable to meet the contractual obligations of the mortgage, actually Mortgage insurance, no matter what kind, protects the lender. 

Mortgage insurance can refer to private mortgage insurance (PMI) and qualified mortgage insurance premium (MIP). What these have in common is an obligation to make the lender or property holder whole in the event of specific cases of loss. 

Mortgage insurance (PMI) is a prerequisite for getting a conventional mortgage loan. Conventional loan When you pay the installments or the house price goes up (or rather the house gets 20% Equity) the bank is obliged to cancel your loan insurance.

An FHA loan is a government loan and those who have an FHA mortgage must buy this type of insurance, regardless of the size of their down payment.