Starfleet is the exploratory and defence service of the United Federation of Planets. Its primary mandate and purpose is that of scientific discovery and development, with the vast majority of its resources and personnel dedicated to missions of exploration and research. Alongside that stands the work of Starfleet diplomats, representing the Federation's interests abroad through the pursuit not just of peace and stability, but Federation ideals of justice and equality. Finally, Starfleet provides security to Federation citizens, including protection of shipping lanes and borders and, when necessary, military deployment. As such, Starfleet units are often highly flexible, capable by training and ideology of undertaking a wide range of missions.
Many of Starfleet's origins can be found in the organisation of the same name founded by the United Earth in the early-22nd century. Exclusively an exploratory body, its militarisation developed first at the encounter of dangers in deep space, but accellerated with the Xindi Crisis and Romulan War of the 2150s. This war included military action alongside the navies of other future Federation members, and paved the way for modern Starfleet. When the Federation was founded it was with ambitions of peace and exploration, and so Starfleet was selected as the service to retain. Unlike the armed services of the Andorians, Vulcans, or Tellarites, it maintained a primary mandate of scientific operations, and so these services were amalgamated into the new, combined organisation, its operations overseen by Starfleet Command.
For the last two and a half centuries, Starfleet has maintained a mission primarily of science and diplomacy, pushing the boundaries of Federation knowledge. It has mobilised for war on several occasions, taking heavy losses in the Klingon-Federation War of the 2250s, and maintaining the tense peace with the Klingon Empire for 50 years after until the Khitomer Accords. Numerous missions of exploration have provided opportunities for colonisation and diplomacy with potential member worlds, expanding the Federation's borders greatly in this time.
Starfleet stepped up its defensive protocols after the discovery of the Borg threat in the 2360s, which proved timely with the outbreak of hostilities with the Klingon Empire and the Dominion over the next decade. While it attempted to return to a mission of peace and diplomacy in the aftermath, the crises of the Romulan Supernova and the Attack on Mars changed the course. After devastating losses to its fleet power and a shift in Federation policy to focus on domestic affairs, Starfleet's exploratory operations have been massively reduced over the last decade and a half. For much of this time, the majority of Starfleet resources have been dedicated to domestic scientific research, and its own border and internal security.
In the late 2390s, the makeup of Starfleet Command shifted as officers who had been on the front line of the post-Dominion War rebuilding and diplomacy entered the Admiralty. A small group of these lobbied for Starfleet to return to its original mission, and while they were largely unsuccessful, it has resulted in the 'experiment' of the reassignment of the 4th Fleet to missions of deep space exploration, humanitarian aid, and diplomacy beyond the Federation's borders. These operations remain, however, outliers in a largely internally-focused Starfleet.
See also: Starfleet Command Staff
As Starfleet is a service of the Federation, the Federation President has direct commanding authority over the service. The Federation Council also has many means of influencing Starfleet operations and has even issued orders on occasion. However, day-to-day operations are managed by Starfleet Command, under a commander-in-chief. Starfleet Command can also refer to the larger body of Starfleet leadership, including the Fleet commanders and directors of Starfleet departments. Adjacent to these hierarchies are those of sector commands, who oversee permanent operations within the sectors of Federation space.
Starfleet Academy is the body responsible for the training of its officers. The term is often used interchangeably with the main campus in San Francisco, but Starfleet Academy has multiple facilities across the Federation to support both the vast number of officer candidates and the need for highly-specialised training.
Starfleet personnel are organised in a naval-derived rank structure with a chain of command, and are either enlisted personnel or officers.
Officers have received long training at Starfleet Academy, either with a command or management element to their training, or for particularly specialised education. These commitments tend to lead to long careers in Starfleet that can span decades. Enlisted personnel receive shorter training and tend to serve in either more broad roles, or specialised positions which nevertheless do not require years of education. While many enlisted personnel have similarly long careers, it is quite common for them to serve only one or two tours of duty before returning to civilian life. This can be out of a desire to see the galaxy, a desire to serve the Federation, or simply an opportunity for training and experiences they could not easily get elsewhere, while not sacrificing other life ambitions or commitments.
All officers outrank all enlisted personnel; even the lowliest ensign may give orders to a master chief petty officer. In both practice and policy this is not an assumption of a young officer's superior judgement by training, however. Junior officers are either trained and developing unit leaders with the skills and education to manage teams and departments, deploying such seasoned personnel to best meet the broader needs of the assignment, and trusting them to execute their orders with the benefit of their years of experience. Or these junior officers are highly trained specialists, given operational seniority over more experienced enlisted personnel on assignments where this training qualifies them to make such decisions. Starfleet principles of respect and diversity help ensure the chain of command does not demean veteran non-commissioned officers in such a way. In turn, enlisted personnel recognise that young officers have been trained for their duties and given assignments where they make strong leaders or managers, rather than disrespecting them for their age or lack of field knowledge. This structure helps provide well-rounded teams of different learning styles and experiences.
Science and Exploration
This has contributed in vast part to the Federation's growth, for no other galactic power possesses such robust exploratory resources, and the Federation has thus been able to expand through discovery of worlds to colonise and new member species.
Starfleet's scientific missions have contributed to its continuing position at the cutting edge of technological developments, which has compensated in large part for its limited militarisation.
Indeed, Starfleet has mobilised on multiple occasions for defensive action beyond interdiction of piracy, albeit with mixed results. The Klingon-Federation War of the 2250s saw Starfleet taking massive losses at the hands of the war-like Klingon Empire, and after the war it remained resistant to calls for reform.
Starfleet's commitment to peace and protection has won many victories in itself. A prime example is the sacrifice of the USS Enterprise-C, one of Starfleet's greatest ships of the period, which in 2344 responded to a distress call to protect the Klingon outpost of Narendra III. The Enterprise was lost and militarily the mission had always been a likely lost cause, but Starfleet principles dictated some effort at rescue was necessary. Ultimately, the sacrifice was seen as highly honourable by the Klingon Empire, and paved the way to the current, long-standing close alliance.