Hunger is a sensation experienced when one feels the physiological need to eat food. In contrast Satiety is the absence of hunger; it is the sensation of feeling full. Appetite is another sensation experienced with eating, however, it differs from hunger; it is the desire to eat food without a physiological need. The often unpleasant feeling of hunger originates from the hypothalamus releasing hormones that target receptors in the liver. Although a healthy, well-nourished individual can survive for weeks without food intake, the sensation of hunger typically manifests after only a few hours without eating and is generally considered to be unpleasant.

Hunger is also the most commonly used term to describe the social condition of people who suffer from a chronic lack of sufficient food and constantly or frequently experience the physical sensation of hunger. See Hunger (malnutrition).

When hunger contractions start to occur in the stomach, they are informally referred to as hunger pangs. Hunger pangs usually do not begin until 12 to 24 hours after the last ingestion of food. A single hunger contraction lasts about 30 seconds, and pangs continue for around 30–45 minutes, then hunger subsides for around 30–150 minutes. Individual contractions are separated at first, but are almost continuous after a certain amount of time.Emotional states (anger, joy etc.) may inhibit hunger contractions. Levels of hunger are increased by lower blood sugar levels, and are higher in diabetics. They reach their greatest intensity in 3 to 4 days and may weaken in the succeeding days^{[citation needed]}, although research suggests that hunger never disappears. Hunger contractions are most intense in young, healthy people who have high degrees of gastrointestinal tonus. Periods between contractions increase with old age.

The horse (Equus ferus caballus) is one of two extant subspecies of Equus ferus, or the wild horse. It is an odd-toed ungulate mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today. Humans began to domesticate horses around 4000 BC, and their domestication is believed to have been widespread by 3000 BC. Horses in the subspecies caballus are domesticated, although some domesticated populations live in the wild as feral horses. These feral populations are not true wild horses, as this term is used to describe horses that have never been domesticated, such as the endangered Przewalski's Horse, a separate subspecies, and the only remaining true wild horse. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, size, colors, markings, breeds, locomotion, and behavior.

Horses' anatomy enables them to make use of speed to escape predators and they have a well-developed sense of balance and a strong fight-or-flight instinct. Related to this need to flee from predators in the wild is an unusual trait: horses are able to sleep both standing up and lying down. Female horses, called mares, carry their young for approximately 11 months, and a young horse, called a foal, can stand and run shortly following birth. Most domesticated horses begin training under saddle or in harness between the ages of two and four. They reach full adult development by age five, and have an average lifespan of between 25 and 30 years.

Bell may refer to: