What is Loan-to-value Ratio?

Legal Definition
The loan-to-value (LTV) ratio is a financial term used by lenders to express the ratio of a loan to the value of an asset purchased. The term is commonly used by banks and building societies to represent the ratio of the first mortgage line as a percentage of the total appraised value of real property. For instance, if someone borrows $130,000 to purchase a house worth $150,000, the LTV ratio is $130,000 to $150,000 or $130,000/$150,000, or 87%. The remaining 13% represent the lender's haircut, adding up to 100% and being covered from the borrower's equity. The higher the LTV ratio, the riskier the loan is for a lender.

The valuation of a property is typically determined by an appraiser, but a better measure is an arms-length transaction between a willing buyer and a willing seller. Typically, banks will utilize the lesser of the appraised value and purchase price if the purchase is "recent" (within 1–2 years).
-- Wikipedia