The Warranty Deed is primarily used by "arms-length" parties (i.e. not friends or relatives) because it provides the buyer with certain assurances related to the seller's right to sell the property.
A "Special Warranty Deed" assures the buyer that the seller has not done anything to the property while the seller owed it that would damage the title or marketablility of the property.
The Special Warranty Deed does not warrant title to the property for anything that happened prior to seller owning the property.
A "General Warranty Deed" assures the buyer that title to the property is free and clear of liens from even before seller owned the property. In most instances, it would be better for the buyer to require a General Warranty Deed than a Special Warranty Deed simply because it provides more protection to the buyer.
Another common form of conveying property is the Quit Claim Deed.
This type of conveyance is often used between family members because it simply tranfers one family member's ownership interest in a piece of property to another family member. There are no warranties as to the title or marketability of the property.
Other forms of conveying property include the Enhanced Life Estate Deed, Transfer on Death Deed, Life Estate Deed.