Hereditary succession is when a person dies without leaving a will and their property is passed on to relatives in a specific order. The order in which property is passed on is spouse/domestic partner first, then children, then parents, then siblings, then nieces and nephews, and from there it goes to the closest living relative.
If a person does not leave a will before they die, it can create confusion as to who should get the person's property after their death. Hereditary succession serves the purposes of solving this problem. Without hereditary succession, many people may try to lay claim to the property. However, with hereditary succession, there is a formal order which clearly specifies which relative has the right to the property first, second, third, fourth, etc.