The term "Reserve Components" refers to the parts of a nation's military that are not in active service but can be called upon when needed. In the United States, this includes the Army Reserve, Navy Reserve, Air Force Reserve, Marine Corps Reserve, and Coast Guard Reserve. These forces allow the military to maintain a larger pool of trained personnel without the costs associated with a full-time standing army. Members of the Reserve Components typically have civilian jobs or attend school while training part-time. They participate in regular drills and training exercises, ensuring they are prepared to support the active duty forces during emergencies, natural disasters, or military operations.