The term "Third Rail" refers to a method of supplying electric power to trains, particularly in urban transit systems like subways. It consists of a metal rail that runs alongside the tracks, providing electricity to the train's motors through a contact shoe. This system is efficient for powering trains in densely populated areas where overhead wires may be impractical. In a broader context, "Third Rail" is also used metaphorically to describe sensitive political issues that are often avoided due to their controversial nature. Topics like social security, abortion, or gun control can be considered third rails in political discussions, as they may provoke strong reactions and are often seen as too risky to address openly.