Negotiation is back in style. It's not uncommon for buyers and sellers to have many rounds of counteroffering back and forth before they arrive at a contract that is completely agreeable to all involved. When this is accomplished, the contract is ratified.
However, there is another important element involved in ratifying a contract. Until a residential purchase contract is completely signed, and the final signed documents are delivered back to the other party or that party's agent, the listing is not sold.