This is the point of no return. Once contracts have been exchanged the purchase is set in stone, legally speaking.
It may sound like a formal process where bundles of papers are handed over a table, but in reality it is likely to be a telephone conversation between the buyer’s conveyancer and the seller’s conveyancer. They will agree the terms of the contract, including the final purchase price, the amount of deposit paid and confirm the completion date.
Once this conversation is over they will send their signed contracts to each other and the transaction becomes legally binding.
Because there is no going back, exchange of contracts cannot take place until every single issue in the transaction is resolved.