Ki (気, Spirit), also called Chi, or simply Energy, is the main source of energy for characters in the Dragonball universe. It is essential for even the most basic energy attacks. Ki is also used to determine one's life force, as if a person is dead, their ki ceases to exist in the realm of the living. It is also used to determine how powerful a being is, as the more ki a person possesses, the stronger the person usually is and the more powerful of techniques they are capable of using.
Ki is made up of three components: Energy (元気, Genki), Courage (勇気, Yūki), and Mind (正気, Shōki). It can also be positive or negative depending on the user and their personality (whether or not they are evil or good). Ki comes in a variety of colors, which is also is user specific, though the most common colors are white, blue, and yellow. As above mentioned, ki can be used for special energy attacks, but it can also be focused to allow users to Fly. When powering up, or in a powered up state, ki energy takes the form of an aura around the user's body.
Power Level Edit
The amount of Ki one is using at any given time is referred to as their Power Level (戦闘力, Sentō Ryoku; lit., "Fighting Strength"). Power levels can be used by two opponents to determine how a battle will turn out. Usually, beings of higher power levels will beat beings of lower power levels, though there are many exceptions.
Power levels can also fluctuate. A ki user is capable of both bulking up and concealing his or her ki depending on the amount they possess. This can be very useful in a fight, as it can be used to deceive opponents when in a difficult battle. Often times, an opponent who underestimates his or her foe's power level can come out losing a fight they would have otherwise won had they known their opponent's true strength.
Ki can be increased by powering up. Sometimes this requires a transformation, but basic ki users can charge their ki in order to have access to more of it. A ki user can only charge up with ki they have. This means that powering up does not create new ki, but rather, gives the user access to more of his or her ki energy.
Life Force Edit
Ki also acts as a form of life force, as all beings possess at least some innate ki. A healthy being will emit vibrant ki, allowing them to be sensed by those with ki-sensing abilities. Those that are badly injured, or are near death, on the other hand, have low ki that can sometimes only be sensed by the most keen sensors. Those beings that have died contain no ki at all, and therefore, cannot be sensed.