Deep-litter housing means that hens are not confined to batteries but allowed to move around freely in the entire building and scratch on the fresh litter. They lay their eggs in dedicated nests. Apart from the deep-litter system, its modernised version i.e. voliere housing is also becoming widespread. In this system hens are also kept on deep litter in a certain part of the floor area. If the egg code begins with 2, consumers can be sure that such eggs come from animal-friendly production. Actually, the code of deep-litter eggs also begins with 2.