......Phoebe the youngest sister returns to the family house, after living in New York since their Grams died. It is only by being all together in house that they receive their powers, which they were destined to have. The sisters all lead very independant lives, and the thought of being witches is very scary to them to the begin with. Which is made made easier when they find out they have a Whitelighter, Leo to guide them, who happens to be the target of a friendly sibling rivalry between Piper and Phoebe.

Prue the oldest sister, had to help raise her siblings, as their mom died when they were very young and their grams raised them. She is very driven and ambitious, and doesnt really connect with her younger sibling, Phoebe.

Middle sister Piper plays mediator between both of her sisters, hopelessly trying to bring them together. She gave up her passion for food to make sure they could pay their Grams' hospital bills. She struggles the most with becoming a witch and not being able to lead a normal life.

Phoebe the youngest sister, the most carefree and the one who gets into trouble without thinking about the consequences, is the most open to their powers.

Their magic and The Power of Three brings the girls togther as witches and as sisters. As their powers grow so does the range of demons they must fight. They experience a wide range of things from realising they are good witches, trying to get a love life, finding balance in their lives with fighting demons and paying the rent, and the loss of losing loved ones.
In the end of the third season tragedy occurs when the eldest sister Prue is killed by a demon. Bringing an end to the Charmed Ones and The Power Of Three.
That is until the girls' mom decides to tell them about a fourth sister, a half sister. A sister witch, who is also half whitelighter. A result of a love affair that Patty(their mom) had with her whitelighter Sam. Paige the other sister, was given up when she was born to protect her from evil, and to make sure the girls were given the right to live out their destiny as the Charmed Ones.
With the Power of Three together again, the girls are once again targets for all the underworld. They have to try and adjust to their new roles they have. The next seasons see them vanquish all manner of demons, have babies, find love and lose love, and come in contact with all kinds of magical creatures.