PIPER
Piper is the middle Halliwell sister, now the eldest. She has the ability to stop time. This power enables her to freeze everything around her. Later she learned how to freeze and unfreeze certin poeple and body parts. This power helps to stop the evil in it tracks giving the Charmed Ones time to either vanquish, or gives them time to get away. Her Second power came in Season 3 when she learned that her first power slowed down molecules, now she has the ablitly to speed them up. Which means watch out she can blows things up. With comes in handy when you don't have a vanquish handy. Now in Season 4 she is getting a handle on her powers again, being able to freeze or blow things up, in Season 3 she would wave her hands and didn't know what would happen. Piper is now starting to use powers that her baby has.
PHEOBE
Phoebe is the youngest Halliwell now the middle sister. She has the ability of premonitions Better known as the power that see's past and future events by touching objects, or people with her hands. This power helps to stop bad things from happening to inoccent people. In Season 3 she aquired the ability of levetation. Which means she can fly. Well in a way. This is her first active power and it's taking some time to learn how to control it. This power comes in handy with her kick butt moves she uses to fight when her sisters aren't around to help. Now in Season 4 she is able to control her Levatating, and her premonitions are stronger Seen in Charmed Again when she actually fell over from a premonitoin she got.
PAIGE
Paige is the newest sister the youngest. She has many powers her main power is Telekentic orbing, this is when she says something like Lamp and it appears in her hand. Or she can wave her arm and make that object she is orbing fly through the air. She also has the powers of a whiteligher healing, and orbing, Before she could only orb when she got really scared, now she is able to somewhat orb around the house, and across town as seen in The Three Faces of Phoebe. She has also developed sensing powers.
PRUE
Prue being the eldest got her Power first, the power to move things with her mind. At first she could only do it by squinting her eyes, but then in season 1 she learned to do it with her hands. Then in Season 2 she was the first to recieve her second power. Astral Projection. She could move things with her mind, Why not herself. Over the Years Prue's power became strong. Her power was sometimes the only one usuable on powerful demons.