HO scale

HO scale (H0 scale in continental Europe) is the most popular scale of model railway in most of the world (outside the United Kingdom, where the slightly larger 00 gauge is most common).

The name HO is derived from the fact that its 1:87 scale is approximately half that of 0 gauge.

H0 scale trains first appeared in the United Kingdom in the 1930s, originally as an alternative to 00 gauge, but could not make commercial headway against the established 00 gauge. However, it became very popular in the United States, where it took off in the late 1950s after interest in model railroads as toys began to decline and more emphasis began to be placed on realism in response to hobbyist demand.