Exchange day is a biggie – this is when everything becomes legally binding between you and the other party. Up until this point, either side could have walked away without (too many) consequences.
Essentially, you’ll both review and sign identical contract agreements, then your conveyancers will formally swap (exchange) them. Once exchanged, you’re legally bound to the property transaction. If someone pulls out now, there are penalties. The seller would have to return the exchange deposit, while the buyer risks losing it completely.
Not only that, walking away post-exchange likely means wasted time and money too.
It’s rare for people to pull out after contracts have been exchanged, so try not to overthink it too much. Typically, exchanging means the time for worry is over, and you can be confident that you are locked into your property transaction.