The type of wiring in residential homes generally depends on when the home was built, where it was built and if it has been updated. In older homes, knob and tube type wiring was the norm, replaced later by plastic-sheathed wiring.
Often, newer electrical panels and updated wiring are good indications that a home has been maintained to code. It is always a good idea to have any electrical work completed by a licensed professional. The investment will not only make your home a safer place to live, but will also pay dividends for you when it is time to sell.
Lastly, when staging your home for buyers, avoid using extension cords or outlet splitters. Reducing this type of electrical clutter will keep buyers focused on your home, and not its outlets!