A mortgage that is the primary lien against a property.
A "first mortgage" is the primary lien against a property. The term is usually coined "first mortgage" only when a "second mortgage" is obtained on a property. A "second mortgage" is a lien that is subordinate to the first mortgage. Usually, the interest rates on second mortgages are slightly higher than the interest rates on a first mortgage. The amount of a second mortgage you can take out will depend on the equity you have built up in your home, the appraised value of your property, your credit history, and any other liens you may have against your property, such as a home equity line of credit.
Borrowers will typically get a second mortgage to tap into the equity they've built in their home -- and use that for home improvements, debt consolidation, medical bills, or other purposes. You apply for a second mortgage with the same process you follow for a first mortgage. However, some of your closing costs may be less.
When you have a first and second mortgage, you theoretically have two loans, both requiring interest and principal payments.