The craft in the Halliwell line originated with a witch named Melinda Warren. Born in Virginia in the 1670s, Melinda and her family moved to Salem, Massachussetts, the setting of the famous Salem Witch Trials. Unfortunately, Melinda was hanged during the trials but because of the generosity of those who took care of her daughter after her death, her line was able to continue and eventually develop into the strongest good magic of all time.
A prophecy foretold of the Charmed Ones -- three sisters, descendents of Melinda Warren who were destined to become the most powerful good witches of all time. One sister would have the ability to move things with her mind, the second would be able to stop time and the third to have premonitions, visions of the future. Prue, Piper and Phoebe Halliwell did not suspect that they were witches, let alone the Charmed Ones. When their mother was pregnant with Phoebe, a warlock named Nicholas tricked their mother and captured her, forcing her to bless a ring which would grant him immunity to the sisters' powers. In order to protect her grandchildren from Nicholas, the sisters' grandmother bound their powers after Phoebe was born and afterwards their mother and grandmother hid the fact that they were witches. Consequently, Piper and Prue forgot that they had once had powers and Phoebe never had the opportunity to remember.
The sisters did not discover they were witches until twenty years later after their grandmother died. Phoebe returned from living in New York, where she moved after Grams passed away, and moved in with her sisters back into the manor in which they grew up. While cleaning the house, Prue stumbled upon a spirit board that the girls' mother gave them when they were young. When Phoebe began asking the board questions, the pointer began moving by itself and spelled out the word "attic." The sisters dismissed the spirit board's message, but later that night Phoebe was led into the attic, which had been closed off for as long as she and her sisters could remember but somehow that night the door opened. A strange ray of light led her to an old trunk in which she found the Book of Shadows, an ancient volume filled with magical spells and incantations that had been added to by each generation of Warren witches. She read one of the incantations aloud, reawakening powers inside her and her sisters that they never knew they had.
With their powers came the added responsibility of protecting innocents and the burden of fighting and vanquishing demons and warlocks who began to pursue them. Becoming witches also made it necessary for them to connect as sisters in order to protect themselves as well as others. Making that connection proved a difficult endeavor, but they managed to overcome their differences and finally accept each other.
After Prue died, Phoebe and Piper felt lost and Piper was ready to give up on her magic until they discovered that they had another sister. After the sisters' mother and father divorced, their mother had a forbidden affair with her whitelighter. As a result of that relationship, Paige was born and she presented an opportunity for the power of three to be reconstituted in spite of Prue's death. Hesitant at first to accept a new sister into their lives, Phoebe and Piper realized that they still had an obligation to their powers and to innocent people they were destined to protect. The sisters are slowly beginning to accept each other and trying to form a family again.