Heritage railways and museums listed on this site have been grouped into five general categories:
A railway is something that is long enough to be considered a point to point journey (even if many visitors will simply go to the end of the line and back). That includes standard gauge heritage railways, such as the Severn Valley Railway, and narrow gauge railways of any significant length, such as the Welsh Highland Railway.
An entry categorised as "rides" is a shorter stretch of railway, either a very short point-to-point railway (such as the Lincolnshire Wolds Railway) or a circular railway, often narrow gauge, that is part of a larger attraction (such as the Craigtoun Miniature Railway).
A museum is an institution aimed primarily at displaying historic objects. While many rail-related museums also have short stretches of railway, either standard gauge or narrow gauge, that can be ridden, the main focus is on the collection rather than the experience.
A tramway is an urban, street-running railway, either standard gauge or narrow gauge. Most of Britain's heritage tramways are found in coastal towns, where they form a distinctive part of the seaside attraction.
A funicular, or cliff railway, is a steeply inclined railway running up the side of a hill or cliff face.
The distinctions between different categories can be very fuzzy. Some railways are closer to being rides, some rides may be long enough to be considered by some to be a railway, many railways also have museums, and many museums have rides or demonstration lines that could be considered an entry in themselves. The categories used here are intended to be a guideline rather than a definitive listing.