Elements of Duplo Trains
I deal here only with the current design of Duplo trains, not with the older designs, except for a brief discussion.
Duplo trains have electric locomotives, cars, rail elements and control elements.
Complex layouts can be built:
Some control elements have the form of rails (switches, direction changers) others are independent ("smart" elements).
There are several types of locomotives, of similar designs but very different in capabilities. It remains a mystery to me why some newer types have fewer functions than some older ones.
Cars are also of several types, but they are much less interesting than the locos and the rails.
The rails I discuss here are all of the newer type. There was an older design that was rather less ingenious, so much inferior in fact that I wonder if the team who designed it was perhaps fired, dissolved or otherwise disactivated. The newer design is very good.