Sakura Kinomoto (木之本桜) is the main character in Cardcaptor Sakura. She also has some brief appearances in Tsubasa Reservoir Chronicle and is mentioned in xxxHolic.
In Cardcaptor Sakura, she is the girl chosen to become the new mistress of the magical Clow Cards after Clow Reed, the creator of the Clow Cards and the guardians (Yue and Cerberus), had died. The story develops on Sakura's quest to capture all of the fifty-two Clow Cards, and later on, converting them into Sakura Cards with her own magical power of the stars.
In xxxHolic, Yuko states that Sakura has a boyfriend/sweetheart (Syaoran) that she is currently living with. Sakura gave Syaoran's mother her Star Wand in a dream so that she (Syaoran's mother) could give it to Yuko as the price for the real Syaoran to go to Clow Country after she had a dream that "Syaoran" would meet with his destined person.
Prior to this, Sakura had made a cameo appearance in Tsubasa Chronicle: Tokyo Revelations as a spirit of the feather that Fuuma had, who guided Princess Sakura back to the group. Fans made many speculations, asking whether this meant she was dead or was communicating with her other self. (This happens only in the OVA)
Fan theories about Sakura Kinomoto
Theory 1: Sakura might be Syaoran's mother
The reason for this theory is based on Syaoran's mother having the Star Wand, which Yuko said herself that "there's only one Star Staff" and "the only possesor of that wand being Sakura".
Additionally, Syaoran said Nadeshiko resembled his grandmother. He also recognized the magic circle from CCS as being "my mother's magic circle".
This theory has been proved wrong because Clone Sakura is the mother of Syaoran. Also, the Star Staff was presented to Syaoran's mother in a dream by Sakura Kinomoto.
(see Manga chapter 224)
Theory 2: Sakura Kinomoto is an alternate self to Princess Sakura
In chapter 223, it's revealed that the Clones reincarnate as Sakura Kinomoto and Syaoran Li (as their alternate selves). This would fit in with prior explanations from Yuko, when the Clones entered her shop at first: "their soul is the same"- refering to Sakura Kinomoto and Syaoran Li. This would explain further the reason for them having the same magic circles from the CCS pair, Nadeshiko being Clone Sakura's mother, and having the Star Staff is explained in another chapter where Clone Sakura sees Sakura Kinomoto in a dream, telling her "Everything will be alright".