The Light Card has the ability to control light and turn night into day. It is the sister card to The Dark Card and they must be sealed together, used together, and transformed together. The Light's true form is that of a majestic woman wearing a white crown and clothing with black accents. She is one of the three cards under Cerberus' jurisdiction along with The Firey and The Earthy Cards.
The Light first appeared in Episode 42. The Dark had interrupted Sakura's class play by covering the auditorium in a magical darkness. Sakura tried to find other people, such as Syaoran, who was right beside her during the climax of the play, but could not. Becoming discouraged, Sakura quickly cheered herself up and The Light appeared. The Dark appeared soon, as well, and the two sister cards talked to Sakura. They told her that Light had been in Sakura's heart ever since she scattered all of the Clow Cards when she accidentally used The Windy Card. They also forewarned her about Yue and his Final Judgement, then asked to be sealed together.
The Light is transformed along with The Dark in Episode 69. Eriol Hiiragizawa had finally shown Sakura who he really is and cast a spell over Tomoeda so that everyone that did not have magic would fall asleep. Sakura first confronted Eriol while Cerberus and Yue were busy fighting Spinel Sun and Ruby Moon, respectively. After she transformed all of the other Clow Cards into Sakura Cards, only The Light and The Dark remained. With the combined help of Cerberus, Yue, and Syaoran, Sakura was able to transform The Light and The Dark together and used The Light to turn the night into day.