Who owns the properties being sold?
That really just depends on the property but here are some common scenarios. Sometimes it is being sold by the current owner who is just looking for a quick way to sell his/her property or otherwise doesnt want to fool with the drawn out process of selling in the conventional way. Sometimes the owner has passed on and the property is in probate, and the estate is selling the property at auction either to divide the profits between the heirs or to cover liens backed by the property. Sometimes the property has been foreclosed on, so the bank is selling the property at auction to minimize holding costs. Sometimes the local government has seized a property either for illegal activity, or simply for unpaid taxes, so they will dispose of it via public auction. Finally, there are some auction companies that own real estate themselves, and they are selling the property.