Under the Whyte notation for the classification of steam locomotives, 2-10-0 represents the wheel arrangement of two leading wheels on one axle, ten powered and coupled driving wheels on five axles, and no trailing wheels. This arrangement was often named Decapod, especially in the United States, although this name was sometimes applied to locomotives of 0-10-0 "Ten-Coupled" arrangement, particularly in the United Kingdom.
Other equivalent classifications are:
UIC classification: 1E
French classification: 150
Turkish classification: 56
Swiss classification: 5/6
Russian classification: 1-5-0
These locomotives were popular in Europe, particularly in Germany, and in Russia; British use of the type was confined to the period during and after World War II. In the United States, the 2-10-0 was not widely popular but was a favorite of a small number of railroads which operated mostly in mountainous terrain.
The 2-10-0's main advantage was that five out of six of its axles were powered, meaning almost all the weight was available for traction rather than being distributed over pilot and trailing wheels.