Lightsaber instructors have summarized thousands of years of combat techniques into seven basic forms, each with distinct philosophies, maneuvers, and defensive postures. Jedi Knights study multiple forms, but most tend to have a preference or strength in one.
Form I: Shii-Cho (Determination)
This is the most basic of all forms. It is taught to younglings as a foundation, and includes the fundamentals of stance, attack, parry, and landing a "Mark Of Contact." This is a style used by Ahsoka Tano.
Form II: Makashi (Contention)
The maneuvers of Form II comprise a formal style of lightsaber-to-lightsaber combat. In the hands of the most skilled masters, the moves can be classical and elegant. It is difficult to penetrate the defenses--to injure, or damage the weapon--of a true Form II master. This is used by Count Dooku.
Form III Soresu (Perseverance)
This passive form enforces defense through efficient body movements, such as reducing the size of your target area. This form is best used to deflect blaster strikes. This is used by Obi-Wan Kenobi.
Form IV: Ataru (Aggression)
A physically demanding style, this fighting form includes acrobatic jumps, flips, and weaves. It is truly the mark of a Force-skilled warrior to exhibit the amazing agility required by this form in combat. This is used by Yoda.
Form V: Shien (Resilience)
A more offensive version of Form III, this form uses techniques including the redirection of blaster strikes toward an opponent, or the use of defensive parries to force an attacker to drop his guard. This is used by Darth Vader.
Form VI: Niman (Moderation)
This form seeks to balance out the strengths of the previous forms through a combination of moderation and calm. A Jedi who has mastered Form VI wields amazing lightsaber skill, but does not focus of power or aggression. This form is used by Cin Drallig, who is actually the finest swordmaster away from the battlefield.
Form VII: Vaapad (Ferocity)
This form is extremely dangerous and should only be attempted by the most disciplined Jedi Masters. It is a strong style of combat that requires intense energy. Such narrowed focus comes dangerously close to the aggressive instincts that surface from the dark side. This is used by Darth Maul.