Mortgage law is a complex body of legislation that varies widely from state to state. As a rule, a mortgage is defined as the transfer of the ownership of (or interest in) land or real property as collateral for a loan. Mortgage law generally requires the loan to be repaid in set installments for a specific period of a time, at a specific interest rate. Many mortgages may also include promissory notes, an acceleration clause and other terms and conditions. When a borrower defaults on a home loan obligation, mortgage law allows for foreclosure of the property. Mortgage law is best explained by a lawyer specializing in that area of law.