Live steam

Live steam is steam under pressure, obtained by heating water in a boiler. The steam is used to operate stationary or moving equipment.

A live steam machine or device is one powered by steam, but the term is usually reserved for those that are replicas, scale models, toys, or otherwise used for heritage, museum, entertainment, or recreational purposes, to distinguish them from similar devices powered by electricity or some other more convenient method but designed to look as if they are steam-powered. Revenue-earning steam-powered machines such as mainline and narrow gauge steam locomotives, steamships, and power-generating steam turbines are not normally referred to as "live steam".

Steamrollers and traction engines are popular, in 1:4 or 1:3 scale, as are model stationary steam engines, ranging from pocket-size to 1:2 scale.

Railroads or Railways

Ridable, large-scale live steam railroading on a backyard railroad is a popular aspect of the live steam hobby, but it is time-consuming to build a locomotive from scratch and it can be costly to purchase one already built. Garden railways, in smaller scales (that cannot pull a "live" person nor be ridden on), offer the benefits of real steam engines (and at lower cost and in less space), but do not provide the same experience as operating one's own locomotive in the larger scales and riding on (or behind) it, while doing so.