A lightning rod is a metal narrow piece or rod, typically of copper or similar conductive material, used as part of lightning security to guard tall or isolated structures from lightning damage. Its formal name is lightning finial. Sometimes, the system is informally referred to as:
A lightning conductor,
A lightning arrester, or
A lightning discharger.
However, these terms really refer to lightning guard systems in general or specific mechanism within them.
Lightning rod dissipaters make a structure less nice-looking by which charges can flow to the air around it. This then reduces the voltage between the point and the storm cloud, making a strike less likely. The most common charge dissipaters appear as slightly-blunted metal spikes sticking out in all information from a metal ball. These are mounted on short metal arms at the very top of a radio antenna or tower, the area by far most likely to be struck. These devices diminish, but do not eradicate, the risk of lightning strikes.