In Whyte notation, a 2-8-0 wheel arrangement is called a Consolidation.
The numbers describe two leading wheels on one axle, eight coupled driving wheels on four axles, and no trailing wheels. The name came from the Lehigh and Mahanoy Railroad’s Consolidation, a locomotive built in 1866 and often credited as the first example to receive the name.
The type became especially valuable for freight service because its eight driving wheels supplied strong adhesion for starting and hauling heavy trains. From the late 19th century into the early 20th century, Consolidations were built in large numbers in the United States and elsewhere. Their strength was moving heavy loads at relatively modest speeds, rather than fast passenger running.
The main mix-up is with similarly named Whyte types: a 2-6-0 is a Mogul, a 2-8-2 is a Mikado or Mike, and a 2-10-0 is a Decapod. A tank locomotive with the same arrangement may be written 2-8-0T.