OK, I follow that now. Completely different down here in Oz. I'll talk about the process in the state of Victoria where I am but I don't think its significantly different in other states and territories.
Contract and a bunch of other documentation is actually prepared, usually by the vendor's solicitor/conveyancer at the beginning of the process. By law this documentation must be provided to prospective purchasers, whether the sale method is private treaty or auction. When an agreement is reached with a purchaser both parties sign the contract and the purchaser pays a deposit, usually 10% of the purchase price. If a private sale there is then a 3 day cooling off period during which the purchaser can pull out, in which case they forfeit 10% of the 10%. if they don't pull out the contract is locked in at the 3 day mark, If an auction there is no cooling off period and the contract is locked in immediately.
From that point on both parties are obligated and the seller cannot sell it to someone else, even for a higher price, unless the purchaser fails to follow through and defaults (in which case they forfeit the whole 10% deposit). There is then the settlement period, defined in the contract, usually 90 days but sometimes as short as 30, while the legal and technical aspects of transferring the land title are undertaken. On settlement day, the parties representatives meet (in cyber space these days but historically all in the same room), where the final legal steps are taken and the balance of the purchase price is handed over. At that point, the purchaser would get a call that they can come and pick up the keys from the selling agent's office, the vendor being obligated to have the place at "vacant possession" stage by then.
Ordinarily, contracts that are conditional on anything else, be it sale of the purchaser's property, bank finance or anything else, are unheard of here these days, but we have very much been in a seller's market for 20 or more years.
