Halal is Arabic for permissible. Halal food is that which adheres to Islamic law, as defined in the Koran.
The Islamic form of slaughtering animals or poultry, Bhabha, involves killing through a cut to the jugular vein, carotid artery and windpipe.
Animals must be alive and healthy at the time of slaughter and all blood is drained from the carcass. During the process, a Muslim will recite a dedication, know as tasmiya or shahada.
There is debate about elements of halal, such as whether stunning is allowed.
Stunning cannot be used to kill an animal, according to the Halal Food Authority (HFA), a non-profit organisation that monitors adherence to halal principles.
But it can be used if the animal survives and is then killed by halal methods, the HFA adds.