Why can helicopters take off and land vertically?

Harrier is the first jet plane in the world to realize vertical take-off and landing. Its engine is different from the general jet plane, and it can generate thrust in two directions, namely, vertical upward thrust and horizontal forward thrust. From the appearance, its engine is very similar to a jumpsuit, with two nozzles at the front and back, and these four nozzles can rotate at the same time. When the plane takes off, the four nozzles deflect downward at the same time until they are completely perpendicular to the ground. The thrust generated by the engine lifts the plane like four invisible pillars through the vertical nozzle. When the plane is in the air, the pilot will gradually control the nozzle to rotate backwards, which will generate a horizontal thrust. The weight of the plane is supported by the lift generated by the wing, and the thrust generated by the engine pushes the plane forward. When the plane lands, when the nozzle is completely perpendicular to the ground, the lift on the wing disappears, because the plane is hovering in the air and has no forward power, and the weight of the plane is completely supported by the vertical thrust generated by the engine. Then, the pilot began to turn down the throttle and reduce the fuel supply of the engine. The vertical thrust gradually became smaller, and the plane began to slowly descend until it finally landed. Therefore, the whole take-off and landing process of Harrier aircraft can be completed only by an open space, thus ending the history that jet aircraft can only take off and land on the runway.