Coventional also known as Conforming Mortgage Loans are mortgage loans that meet the credit and income guidelines of the government sponsored enterprises of Fannie Mae and/or Freddie Mac.
Under their eligible financing guidelines, investors (buyers of the mortgage & note) are offered the comfort of knowing that loans approved by Fannie Mae & Freddie Mac guidelines have a low risk of defualt.
Under Fannie Mae & Freddie Mac underwriting guidelines if you borrower more than 80% of the value of your home you are required to have a mortgage insurance policy that protects the investor (owner of your mortgage) in case you default.