Loan-to-value ratio (LTV)
Loan-to-value ratio (LTV) compares your mortgage balance with the home's appraised value, or the sale price if that is lower, shown as a percentage.
New Jersey example
Say you buy a made-up $400,000 home in Edison that appraises at $400,000, and you put $40,000 down. Your $360,000 loan has an LTV of 90%. New Jersey's housing finance agency notes that most lenders generally require mortgage insurance when the LTV is above 80%.
Official source
This is a plain-English summary. Rules and dollar amounts change, so check the official source or a professional before you file or sign anything.