Private Mortgage Insurance (PMI)

PMI insures the lender, not you, against your default, and it's required on US conventional mortgages with less than 20% down. It typically costs 0.3–1.5% of the loan a year. Its removal is the part borrowers miss money on: it must be cancelled on request once you reach 20% equity, and cancels automatically at 22%, but rising home values only count if you request a new appraisal.