The term notice of default refers to a public notice filed with a court that states that the borrower of a mortgage is in default on a loan. The lender may file a notice of default when a mortgagor falls behind on their mortgage payments. Information on notices of default normally includes the borrower and lender's name and address, the legal address of the property, the nature of the default, as well as other pertinent details. A notice of default is often considered the first step toward foreclosure.