Starfleet is the deep-space exploratory and defensive service maintained by the United Federation of Planets. Its principal functions are to advance the Federation's knowledge of the galaxy, advance the Federation's knowledge of science and technology, and the defense of the Federation which is explained more in the defense tab of orientation. Starfleet has also played a significant diplomatic role as it is often the first contact with new civilizations through Starfleet's mandate of deep-space exploration. As well, Starfleet vessels are frequently used to ferry ambassadors while they are on diplomatic missions.