The Naval Postgraduate School (NPS) is the U.S. Navy's institution of higher learning, awarding master's and doctoral degrees. The school is staffed mostly by civilian academics who are experts in their respective fields. The degrees focus on areas that are of use to the military, as the purpose of the institution is to provide officers with additional training to make them more effective in their respective fields. These fields include computer science, mechanical and aerospace engineering, operations research and defense analytics.
In addition to the Navy, the Army and Marine corps send officers to NPS for advanced training. Officers who are interested can express their desire to determine their eligibility to attend. However, the Navy, Army or Marine Corps choose which of their officers will attend NPS as their duty assignment from the pool of eligible applicants. According to the NPS website, officers are selected on the basis of their professional performance, academic record and potential for promotion.
The Air Force Institute of Technology (AFIT) is the Air Force's graduate school. It awards master's and doctoral degrees in fields related to computer technology, engineering and management. Like NPS, AFIT also takes students from the Army, which has no graduate school of its own. Unlike NPS, however, AFIT also awards a number of non-degree certificates for professional development. Selection to attend AFIT is similar to the selection process for the Army, with the Air Force and Army selecting which of their officers will be assigned there.
Getting a master's degree at either NPS or AFIT is not restricted solely to those individuals who are selected to attend. Both institutions have distance learning programs that allow officers, and in the case of AFIT, enlisted men, to earn a master's degree while on other duty assignments. Not every degree program is offered in the distance learning format, so officers interested in this possibility should investigate the school websites to investigate what is offered.