The Carob tree (from Arabic: ???? "kharoub" and Hebrew: ???? Charuv), Ceratonia siliqua, is an evergreen shrub or tree native to the Mediterranean region, cultivated for its edible seed pods. Also known as St John's Bread, the flesh of the pods tastes somewhat similar to sweetened cocoa, but contains no theobromine or other psychoactive substances and is often used as a hypoallergenic, drug-free substitute. (For this reason, it is considered non-toxic to dogs.) Mixed with saturated fats like butter fat or palm oil, it is often used to make a sweet confection, considered chocolate-like by some, that is usually referred to simply as "carob." Carob is claimed to soothe the digestive tract and help with diarrhoea.

This tree grows up to 10 m high. The crown is broad and semi-spherical, supported by a thick trunk, brown rough bark and sturdy branches. Leaves are 10–20 cm long, alternate, pinnate, and may or may not have a terminal leaflet. The flowers are a green-tinted red, small, numerous, and about 6–12 mm long. They are spirally arranged along the inflorescence axis in catkin-like racemes borne on spurs from old wood and even on the trunk (cauliflory). The fruit is a pod which can be elongated, compressed, straight or curved, and thickened at the sutures. Carob is a member of the legume family, and as such its roots host bacteria which convert atmospheric nitrogen into nitrates which can be used by plants to make proteins.

These trees cannot withstand waterlogging, although the root system is usually deep. It grows well in warm temperate and subtropical areas and tolerates hot and humid coastal areas. It is a xerophytic (drought-resistant) species, well adapted to the ecological conditions of the Mediterranean region. It is also one of the few trees present in the altiplanic desert of South America, where it is known as algarrobo.

Carob is not a staple food in the Mediterranean, but provides good sustenance during times when other crops are scarce and is a traditional feed for livestock. It is most commonly put in cakes, icing, and sometimes cookies. The seeds themselves, also known as locust bean, are used as animal feed and to extract locust bean gum, a thickening agent.

Carob pods were the most important source of sugar before sugarcane and sugar beets became widely available. Nowadays, the seeds are processed for the use in cosmetics, curing tobacco, and making paper. The scientific name of the carob tree derives from the Greek keras, "horn", and Latin siliqua, alluding to the hardness and shape of the pod.

The term "carat," or the units by which diamond weight is measured, is derived from the ancient practice of weighing diamonds against the seeds of the carob tree. The system was eventually standardized and one carat was fixed at 0.2 grams.

Dried carob fruit is traditionally eaten on the Jewish holiday of Tu Bishvat.