Dark side (Star Wars)
The dark side of the Force is a fictional moral, philosophical, metaphorical and psychic concept in the Star Wars universe created by George Lucas. The Force is a mystical energy which permeates the Star Wars galaxy; its dark side represents an aspect of it that is not practiced by the Jedi who view it as evil. The Sith view the dark side as good.
As portrayed in all Star Wars-related media, the dark side provides powers similar to those of the Jedi — telepathy, psychokinesis, and precognition — but draws energy from passion, an energy that is enhanced by emotion (generally by anger and rage). Examples include Force lightning, as used by Palpatine (Ian McDiarmid) in Star Wars Episode VI: Return of the Jedi and Star Wars Episode III: Revenge of the Sith, and using the Force to choke people, as used by Darth Vader in Revenge of the Sith, Star Wars Episode IV: A New Hope and Star Wars Episode V: The Empire Strikes Back. While the original films depict the dark side as a general concept of evil, the prequels and Expanded Universe material elaborate on its nature, explaining that it may stem from all strong emotions, both positive and negative. By channeling tense negative emotions, such as anger, jealousy, or greed, into the Force, individuals can attain powers of the Force more easily, but at a consequence. They gain lust for power, and become increasingly self-aggrandizing. Followers of this path are always depicted as corrupt and wicked, engaging in a never ending self-centred pursuit of power.
The Jedi, while recognizing tempting paths to the dark side, know that the dark side is evil and claim that immense restraint must be used in wielding the Force that limit its uses in accordance with justice. Yoda famously says "A Jedi uses the Force for knowledge and defense. Never for attack". The Sith believe that utilizing the full potential of the Force by using the Dark Side is the only means to understand the true nature of the Force. In Revenge of the Sith, Palpatine telepathically reads Anakin Skywalker's mind when he discovers that Palpatine is Darth Sidious, says that he knows that Anakin wants to kill him but is restraining his anger and tells him "I can feel your anger, it gives you focus, makes you stronger." The Empire Strikes Back Darth Vader in a lightsaber duel with Luke Skywalker on Cloud City telepathically reads Luke's emotions and tells Luke "You have learned to control your fear, now release your anger, only your hatred can destroy me." Luke does not give in to Vader's beckoning, but is later beaten in the duel, losing his hand, but survives. In Return of the Jedi, Luke and Vader duel again, Vader again telepathically reads Luke's mind and using Luke's fear of his sister Leia being turned to the dark side, Vader manages to enrage Luke, resulting in Luke unleashing a hate-filled attack against Vader, in which he has succumbed to the dark side and is able to defeat Vader easily with the power of the hatred that he unleashed.
The Sith view the dark side as good, demonstrating one of Star Wars creator George Lucas's central observations that "most bad people think they are good people". Those following the dark side claim it allows an individual to gain the full powers of the Force that followers of the light side cannot attain. Palpatine claims that Darth Plagueis has the power to create life from nothing and save people from dying from natural causes but claims that this power remains a secret.
Lucas uses 'the dark side', and "paths to the dark side", as a devices to suggest the distinction between good and evil is not a distinction between 'us' and 'them' (which is why creatures other than humans possess knowledge of both sides of the force); but rather a battle within ourselves, reflecting the frailty of human nature and our own competing (and equally compelling) internal impulses towards kindness on the one hand, and cruelty on the other.
Original trilogy 
The dark side is first mentioned in A New Hope as Jedi Master Obi-Wan Kenobi (Alec Guinness) is explaining the Force to Luke Skywalker (Mark Hamill). When speaking of his former pupil, Darth Vader, Kenobi says "Vader was seduced by the dark side of the Force." Vader is later shown using the dark side to choke Admiral Motti, an ability portrayed in greater detail in subsequent films. Luke Skywalker uses the same move to choke the guards at Jabba the Hutt's cave in 'Return of the Jedi', which may mean that this is not specifically a dark side power, or to signify potential darkness in Luke, or that it is simply a form of applied telekinesis.
Star Wars Episode V: The Empire Strikes Back elaborates on the dark side's power. Yoda (Frank Oz) tells Luke that fear and anger will pull him to the dark side, and that there is no turning back from a dark path; Vader, meanwhile, entreats Luke to "know the power of the dark side" and become his apprentice.
In Return of the Jedi, Luke comes perilously close to succumbing to the dark side during a duel with Vader, in which the Sith Lord suggests turning the young Jedi's sister Leia to the dark side, sending Luke into a rage in which he nearly kills his father. Vader claims to Luke Skywalker that by joining him on the dark side both of them can channel their powers together to bring an end to the Galactic Civil War and bring order to the Galaxy. Palpatine plays on Luke's fear for the safety of his friends to release his anger and kill Vader, which would turn him to the dark side. Luke, horrified at his own actions, refuses to deliver the killing stroke. Palpatine then attacks with a torrent of Force lightning. His son's cries of pain break the dark side's hold on Vader, and he turns on Palpatine, throwing him down the Death Star's power reactor to his death; in the process, he is mortally wounded by Palpatine's lightning. With his dying breaths, the redeemed Anakin Skywalker (Sebastian Shaw) admits to his son that the good within him had not been destroyed after all, and then becomes one with the light side of the Force.
Prequel trilogy 
In Star Wars Episode I: The Phantom Menace, Yoda explains to a young Anakin (Jake Lloyd) that his fear for losing his mother, Shmi (Pernilla August), could lead him to the dark side; he says "Fear leads to anger; anger leads to hate; hate leads to suffering."
In Star Wars Episode II: Attack of the Clones, a teenage Anakin Skywalker (Hayden Christensen) begins to feel the pull of the dark side when his mother is killed by Tusken Raiders, and he slaughters the entire tribe in a rage.
In Star Wars Episode III: Revenge of the Sith, then-Chancellor Palpatine manipulates Anakin's fear that Padmé, by now his secret wife, will die in childbirth to persuade him into becoming his Sith apprentice. Palpatine first tempts Anakin by challenging the dogmatic view of the world he had learned in the Jedi Temple. When Palpatine promises that the dark side can prevent death, Anakin becomes his Sith apprentice, Darth Vader, and helps the Sith Lord massacre the Jedi and destroy the Galactic Republic. Mad with power, Vader uses the dark side to choke Padmé into unconsciousness when he suspects that she has betrayed him to his former master, Obi-Wan Kenobi (Ewan McGregor). Padme later dies during the birth of their twins (Luke and Leia).
- Kevin S. Decker, Jason T. Eberl. Star Wars and Philosophy: More Powerful Than You Can Possibly Imagine. Open Court. ISBN 0-8126-9583-6.