The United States military has a clear rank structure that is divided into three main groups. Officers have the highest rank, followed by warrant officers and enlisted members.
Each group has its own rank structure, but an officer always outranks a warrant officer, who always outranks an enlisted member. These ranks apply to every branch of the military.
Within each of these groups, there is a numerical rank structure. The name and insignia of each of these ranks varies with each branch of service, but the ranks always ascend in number from lowest to highest.
There is a small group of general officers who are at the highest level of military command. Each branch of service has four rankings for generals, represented by an ascending number of stars. Each branch also has one five-star general who is the highest-ranking overall member of that branch of service. There is a similar position among the enlisted ranks for one member who serves as the highest-ranking non-commissioned officer in each branch of service.
The military chain of command extends upward past these groups into the Department of Defense. The Deputy Secretary of Defense, the Secretary of Defense and the President are at the head of the chain of command.