The term dangerous goods is applied to all substances and objects whose transport may represent a potential threat to the environment, humans, animals and public safety and order. The transportation of dangerous goods is therefore subject to various legal regulations depending on the mode of transport. The regulations concerning classification for the relevant mode of transport determine whether a substance or object is a dangerous goods. Differences are made between the following modes of transport:

- Road (ADR)
- Rail (RID)
- Inland waterway (ADN))
- Ocean (IMDG Code)
- Air (IATA-DGR)

Efforts aimed at harmonization mean that the regulations governing classification for the various modes of transport are being brought into line. However, differences still exist.