Cardcaptors is the english/american dub of the japanese anime Card Captor Sakura (CCS), it was first aired in 2000 by Nelvana.

It tells the tale of a pre teen girl, who accidentaly, while in her fathers study relelases the clow cards, magical cards capable of conjuring anything from elements to the ability to fly, by opening an anicent book.
Prior to this, nobody could open the book so its starts off a storyline of the book choosing Sakura to be its next master. However, as the cards got away, sakura has a mission to complete. Recapture all the cards.
Its a wild ride, as Sakura is joined by her friends, old and new, to help her in whatever, somtimes amazingly ludicrous, ways.