A deed is the legal document that transfers ownership of real property. A Quit Claim Deed conveys ownership and nothing else. The person conveying (the seller) makes no promises of any sort concerning the conveyor's actual ownership or right to possession. If you've ever purchased the Brooklyn Bridge, it was likely by Quit Claim Deed. Contrast with Statutory Warranty Deed.
In WA, there are three sorts of deeds, all defined by statute, including the Quit Claim Deed. The third type of deed is a Bargain and Sale Deed. Under this third type of deed, the grantor (the person conveying ownership) only promises good title during the period of grantor's ownership. A defect that predated grantor's ownership is the grantee's problem.