A warranty deed is the best kind of deed from the point of view of the buyer.  Like a grant deed, a warranty deed contains implied promises that: (1) the property has not been previously sold by the seller, and (2) there are no liens or encumbrances against the property.

A warranty deed, however, goes further.   If a seller signs a warranty deed, he or she expressly promises the buyer that he or she will receive good title to the property and will have the right to quiet possession and enjoyment of the property.  As a result, after the sale, if any third party shows up, and says that he or she has title to the property, or right of possession, then the seller has to defend the buyer against this claim. Civil Code Section 3304.  In other words, a seller who signs a warranty deed is, in essence, providing the buyer with title insurance.

Warranty deeds are very seldom used in California.  Instead, most buyers of property obtain title insurance.