After the death of a loved one it is necessary to sort out their "stuff". This usually involves the collection of the decedent's assets, the payment of any outstanding debts of the decedent and then distributing the assets amongst the decedent's heirs.
Often the administration of the estate requires a court to intervene and appoint a personal representative to handle the affairs of the decedent. This is commonly called Probate and can be required whether the decedent had a will or died without one. If the decedent set up a trust to hold his or her assets then the administration of the trust occurs and is spearheaded by the trustee of the trust. If the decedent held assets in a "non-probate" fashion then it may necessary to coordinate how those assets are to pass. For information on what to do when someone dies go here.