The Borg are an immensely powerful race of enhanced humanoids from the Delta Quadrant.
The Borg implant themselves with cybernetic devices, giving them great technological and combat capabilities.
Different Borg are equipped with different hardware for specific tasks.
Each Borg is tied into a sophisticated subspace communications network, forming the Borg collective, in which the idea of the individual is a meaningless concept.
The Borg exhibit a high degree of intelligence and adaptability in their tactics.
Most successful means of defense or offense were found to work only once, almost immediately after which the Borg developed a countermeasure.
The first known contact with the Borg and the Federation was on stardate 42761 when Q transported the USS Enterprise-D out of Federation space and into the flight path of a Borg vessel heading toward the Alpha Quadrant.
Following this first contact, Starfleet began advance planning for a potential Borg offensive against the Federation.
The anticipated Borg attack came late in 2366, when a Borg vessel entered Federation space, heading for Earth.
Starfleet Tactical planners had expected several more months before the Borg arrival, and thus were caught unprepared.
Enterprise-D captain Jean-Luc Picard was captured by the Borg at the beginning of this offense.
He was assimilated into the Borg as Locutus of Borg, providing crucial guidance to the Borg in their attack.
Starfleet amassed an armada of some 40 starships in hopes of stopping the Borg at Wolf 359, but the fleet was decimated with the loss of 39 ships and 11,000 lives.
As Locutus, Picard explained that the Borg purpose was to improve the quality of life in the galaxy by providing other life-forms the benefit of being part of the Borg collective.
Following the rescue of Picard from the Borg ship, a last-ditch effort to implant a destructive computer command into the Borg collective consciousness was successful in destroying the Borg ship in Earth orbit.