'Stopping Markers' are the signs that can be seen on a station platform and some sidings to advise the driver where to bring his or her train to a halt.
They are useful for longer trains so the driver knows that the whole train is within the platform, and on shorter trains to provide consistency for passengers and ensure the optimum train stopping position.
There have been many variations of stopping markers through the years with Southern Region signs displaying white lettering on a green background, London Midland using red lettering on a white background, GWR using brown lettering on a white background and the Scottish Region using white lettering on a blue background.
In more recent years the main colour scheme for stopping markers has been white and black, but despite this attempt at standardisation, many variants have emerged to cater for different train types such as HSTs or Voyagers etc. Signs can also have more than one number on them to indicate a common stopping point for multiple specific lengthed trains. An alternative to the numbered stopping boards is the 'S' board which indicates that all trains are to stop there, regardless of length.
Stopping boards are a common sight on railway platforms and can enhance a station's appearance on a layout, but few manufacturers are producing them so they often have to be improvised by modellers wishing to display them.