Control of skiing means making turns. With the development of the carving ski, it has become much easier to make turns than was the case just a few years ago. A short description of the skis and their design can help you understand how they work.
Modern skis are flexible lengthwise. For example, if you place the skis between two chairs, you'll find that you can press down on the skis with relative ease, making them bend. This lengthwise flexibility allows the skis to keep continual contact with the snow, even on the most uneven terrain. This is useful because the more contact you have with the snow, the better chance you have of controlling your skis and, hence, your direction and speed.
Modern skis are also torsionally stiff. This ensures that the ski keeps the same angle to the snow along the entire length of the edge. Older skis tend to be soft across the width, making them flatten out in the tip and tail, thereby limiting their grip in the snow. This increases sideways skidding.
Furthermore, an important aspect about carving skis is their shape. These modern skis are shaped like an hourglass; they are sidecut: that is, they are wide at their ends, while narrow at the middle. This shape ensures that they actually turn when you put pressure on the edges. The more extreme an hourglass shape your skis have, the sharper the turn it is possible to make.