model railroad modules are small sections that are put together to make a larger model railroad. Most of the time they have spesifications that allow different owners to mate up with each other with out having to know what in on the other modelers railroad.

"Modules" are sections of layout designed with agreed-upon specifications for size, shape, track locations, etc. Modules are thus interchangeable and may be built by many different people all around the world and may be brought together and operated.