Train refers to the vehicle running on the railway track, which is usually composed of multiple carriages. It is one of the important modern means of transportation for human beings.
The most important machine in human history, early called steam locomotive, has independent track running. According to the load, railway trains can be divided into freight cars and passenger cars. There are also mixed passenger and freight cars, but they will produce a lot of carbon dioxide and pollute the environment.
In the early days, the traditional train was composed of one to three locomotives pulling a number of carriages or carriages. Modern new trains have appeared multiple carriages with their own power. In Shanghai, there is a maglev train line from Longyang Road subway station to Shanghai Pudong International Airport.