Private mortgage insurance
Insurance a lender usually requires on a conventional mortgage with less than 20% down. You pay for it, but it protects the lender if you stop paying.
PMI is usually a monthly charge added to your mortgage payment, though some loans charge it up front at closing or both. The cost depends on your down payment, credit score and loan amount, and it appears on your Loan Estimate.
Federal law lets you ask to cancel PMI on most loans once your balance is scheduled to reach 80% of the home's original value, and it must end automatically at 78% if you are current. FHA and VA loans have different rules.
Example
On a $300,000 home with a $270,000 loan, you can ask to cancel PMI once the balance reaches $300,000 × 80% = $240,000.