A mortgage note, also known as a real estate lien note, is a signed legal document. By signing, one agrees to repay the loan amount as well as any interest that accrues within a specified amount of time. The interest rate is predetermined.
When you take out a real estate loan, you will also need to sign the mortgage (deed of trust) as well as a promissory note. The promissory note contains the terms of loan repayment, while the deed is released to you upon completion of payment.