Lightning rods were originally developed by Benjamin Franklin.
A lightning rod is very simple -- it's a pointed metal rod attached to the roof of a building.
The rod might be an inch (2 cm) in diameter. It connects to a huge piece of copper or aluminum wire that's also an inch or so in diameter.
The wire is connected to a conductive grid buried in the ground nearby.
The purpose of lightning rods is often misunderstood.
Many people believe that lightning rods "attract" lightning.
It is better stated to say that lightning rods provide a low-resistance path to ground that can be used to conduct the enormous electrical
currents when lightning strikes occur. If lightning strikes, the system attempts to carry the harmful electrical current away from the structure and safely to ground.
The system has the ability to handle the enormous electrical current associated with the strike. If the strike contacts a material that is not a good conductor, the material will suffer massive heat damage.
The lightning-rod system is an excellent conductor and thus allows the current to flow to ground without causing any heat damage.
Lightning can "jump around" when it strikes.
This "jumping" is associated with the electrical potential of the strike target with respect to the earth's potential.
The lightning can strike and then "seek" a path of least resistance by jumping around to nearby objects that provide a better path to ground.