That depends:
1. For any property that was held by the deceased as a joint tenant, then their interest in the property automatically goes to the other joint tenant. This includes not only real estate, but also things like joint bank accounts. Unless specified, things owned by more than one person tend to fall into 'joint' ownership.
2. For any interest held as a 'tenant in common' (i.e. not jointly) then the deceased person's share is treated in the same way as if they were the sole owner (both only for that share).
3. For things owned solely it will depend on whether or not the estate needs to get probate. If probate is not needed, then the executors of the estate gain control of the assets as trustees to follow the provisions of the will. If probate is needed (and it will most almost certainly be needed if the estate includes significant bank accounts and/or real estate holdings) then only those persons appointed as personal representatives of the estate by the court in the grant of probate gain control of the property. This is usually the executors - but it doesn't necessarily have to be them.
