At the start of the series in both manga and anime, Sakura is the princess of the Kingdom of Clow who has feelings for Syaoran, her childhood friend.

When she is about to confess her feelings, a mysterious force causes her own dormant magical powers to manifest in the form of feathered wings. When her feathers are scattered across time and space, Syaoran vows to recover all of them because each feather represents a memory Sakura has had since birth and are connected to her heart; without the feathers, she will die.

Fei-Wong Reed (the mysterious villain in the series) reflects on the ability of people like the High Priest Yukito, Princess Tomoyo of Nihon, and Yūko to cross dimensions and comments that the power concealed within Sakura and the ruins in Clow Country surpasses them all.

In order to cross dimensions, Sakura must pay Yūko the thing most important to her and she pays Yūko in an indirect way but her price is pretty much the same as Syaoran - her memories of him. When she awakes in the Hanshin Republic the first person she sees is Syaoran, but she does not remember anything about him, asking "Who are you?"

At times, such as in Ōuto, Sakura comes extremely close to remembering Syaoran but it is quickly erased once more from her memory. Syaoran, having known this would happen previously, will never tell her anything about their previous relationship. At most, all Sakura knows about Syaoran is what she has relearned from the adventures together with Mokona, Fai, and Kurogane, although she knows she knew him previously and he was very important to her. It is also clear that she is falling in love with him once more.

Sakura possesses unnaturally good luck; both Chun Hyang and Yūko call her "a favored daughter of the gods". This is what allowed her to travel dimensions safely until Yūko asks for her good luck as a price. According to Yukito and Syaoran, Sakura also has the ability to "hear" the voices of those who cannot be heard, such as spirits of nature, and to see ghosts. Such as the time in the Country of Jade, she can see Princess Emeraude while others couldn't. She can also see the future in visions, though this ability is unreliable and nothing she has control over.

Sakura's personality is passive and weary, exhausted from her loss of memories. However as the series goes on, she becomes more stronger and independent. Syaoran states, even though she's lost most of her memories, she'll never change. She helps the group whenever she can, whether it's washing dishes or saving their lives.

(Source: Wikipedia)