A warranty deed is a particular type of deed which contains guarantee statements from the seller that the house will be transferred free of something which undesirable. Usually, that means it will be transferred free of any "liens and encumbrances" such as a federal tax lien or previous mortgage.

As a buyer of Real Estate, if you get a loan from a bank, they will absolutely demand a warranty deed as well as "title insurance". The insurance is a guarantee from a title company that if the house turns out to have a lien or encumbrance, the title company will reimburse the buyer for any damages.