The Emotional Electromagnetic Spectrum is an energy field that is fueled by the emotions of all sentient beings. Inadvertantly, sentient beings channeled and created seven unique forms of energy based on their emotions, with a color unique to the emotion. The Maltusians, the oldest known race in existence, were the first to discover and harness this field. Their successor races eventually chose to harness the emotions of several different colors. They also discovered that the farther one is away from the center of the Spectrum, the more control the energy has on the wielder. According to a prophecy in the Book of Oa, the seven colors of the emotional spectrum would be harnessed by seven different Lantern Corps, which would go to war with each other in a conflict called the War of Light and fulfilling the Blackest Night Prophecy.
Here are the seven major lantern rings and the emotions they represent.
Red Lantern Ring - Rage
Orange Lantern Ring - Greed
Yellow Lantern Ring - Fear
Green Lantern Ring - Willpower
Blue Lantern Ring - Hope
Indigo Lantern Ring - Compassion
Violet Lantern Ring - Love
As you can see, three "evil" emotions and three "good" emotions are on either side of the spectrum, anchored by the neutral Green Lanterns in the middle. The further from the middle the ring is on the emotional light spectrum, the more their personality is influenced by that emotion.
Black is the color of the dead and emotionless. It is the colour of the Black Lantern Corps. Black, technically not a colour but more an absence of colour and light, does not appear on the spectrum itself for this reason, as the Emotional Spectrum is a light based energy classification. Those dead or once dead are capable of becoming Black Lanterns.
Still very mysterious, details about the White Lantern Power Ring are still coming to bear. It is known that it has the ability to return the dead to life. Many super heroes who had returned from the dead briefly wielded a White Lantern Ring, but as of now the only hero currently using a white ring is Boston Brand, the former Dead Man.
