Springs

You may findsprings lying every where and you don't care about it, but if you look at its usage, you would pick it up next time. A spring is made from steel and it is turned into loop that is usually shorter when compressed and then becomes elastic and can be stretched.One simple example of the importance of a spring is the pen. There is a pen that when you push the head of the pen comes out and the next time you push it, it is closed. Without the spring this will not work.