"The first duty of every Starfleet officer is to the truth. Whether it's scientific truth, or historical truth, or personal truth. It is the guiding principle upon which Starfleet is based." – Captain Jean-Luc Picard, 2368 ("The First Duty")
Starfleet is the deep space exploratory and defense service maintained by the United Federation of Planets. Its principal functions included the advancement of Federation knowledge about the galaxy and its inhabitants, and knowledge of wissenschaft (the systematic pursuit of all scholarly knowledge, not just science and technology). Starfleet's ancillary duties included the defense of the Federation, and the facilitation of Federation diplomacy.