A number of different numbering and classification schemes have been used for carriages and wagons on Britain's railways, and this page explains the principal systems. Carriages and wagons (either not self-propelled, or part of a multiple unit which has power units distributed throughout a semi-permanent formation of carriages) have frequently had similar arrangements for classification and numbering, so are considered together. There are also links to other pages that deal in greater depth with the particulars of individual types.