Best trains parts

As a child I always wondered how trains work. What does it need to work properly. Are there any factories producing parts for trains? Or perhaps the are just made from a big-train-mother? Real life, of course, changed my childish questions into a grown-up answers. Now I know how it all works. I know there are parts for trains, for it sometimes brake. I know there are specialists and professionals that maintain trains in a good condition. There are people who maintain also the railway for the trains to keep it safe and working properly. It still interests me, for I have become a train driver in my country.