Under the Whyte notation for the classification of steam locomotives, 0-6-0 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles and no trailing wheels. This was the most common wheel arrangement used on both tender and tank locomotives in versions with both inside and outside cylinders.

In the United Kingdom, the Whyte notation of wheel arrangement was also often used for the classification of electric and diesel-electric locomotives with side-rod coupled driving wheels. Under the UIC classification, popular in Europe, this wheel arrangement is written as C if the wheels are coupled with rods or gears, or Co if they are independently driven, the latter usually being electric and diesel-electric locomotives.