Scale 1:80 || 1:87 || H0
Scale H0 or 1:87 is globally the most popular scale. It has been introduced in Germany approx 1935 and derived from the track width of model trains, which explains the "odd" numbers.
A big variety of models and structures from various companies is available and makes it easier to find a particular item than with any other scale. A first choice for hobbyists, who love details.