Why pendulum move

In short pendulum move to complete one oscillation.

The Earth’s gravity attracts the pendulum. When the pendulum is hanging still, the wire and weight are straight and at a 90-degree angle to the Earth as gravity pulls the string and the weight to the Earth. Inertia causes the pendulum to stay at rest unless a force causes it to move. When the wire and weight are moved in a straight motion, the weight and wire are acting under inertia. This means that since the pendulum is now in motion, it keeps moving, unless there is a force that acts to make it stop. Gravity works on the pendulum while it is moving. The moving force becomes less as the force of gravity acts on the pendulum. The pendulum slows and then returns to the starting point. This swinging-back-and-forth force continues until the force that started the movement is not stronger than gravity, and then the pendulum is at rest again.