What is gazumping?

A property sale/purchase does not become legally binding until contracts are formally exchanged.

Either party can walk away from the transaction with no consequences (save for any of their own costs incurred to date such as legal fees or survey costs) up until this point.

Sometimes, somebody will come along and make a higher offer for a property and the seller will accept this offer instead (even if you are weeks/months into the purchase process). If this happens to you as a buyer, you will have been gazumped.