Recent updates on Change

Train changes the track according to the way on which it have to travel. But, How do they change the tracks ?

One of my student told me that yesterday, he found that when he was dipping litmus paper in different liquids, it changes its color. How it is changed...

Technology is increasing day by day. It has made it's impact on the society and on our lives too. I want to know How technology changed our life ? ...