The pastime of building and running model railways has been around at least since the turn of the 20th century. In the beginning model railroading was primarily for children and the trains were built with that in mind. The earliest model railroad layout were O-scale, which are a bit larger than the typical trains older children and adults focus on these days when they do elaborate model railway layouts.
That said, the actual definition of the O-scale is not really standardized, and American and British model trainers each have slightly different specifications. In fact, Soviet and other European countries also had the own particular versions of the O-scale. This meant that trains and accessories don’t always match up if they are bought in other countries or from different manufacturers.
Over the last twenty years there has been an effort to standardize the scale so that it would truly be to scale. The earlier O-scale layouts were not true to their 1/48 scale.
This is important because the recent focus of model railroading is on accuracy and interchangeability. This means you may be able to use the products from different companies in your O-scale layout. In the past the British used a slightly different O-scale for their trains which were more for adults. With the new improvements in the O-scale, these differences might disappear.
The O-scale layout has a very long and convoluted history, but things are getting a little easier for the model railroader who demands a true standard to get behind when starting out on the adventure of railroading. Perhaps it will spawn a new generation of Internet international railroading where trains, buildings, landscapes and props could be traded across the ocean. It would certainly allow a greater range of choice in products if there were truly an international O-scale layout standard.