Food is any substance normally eaten or drunk by living organisms. The term food also includes liquid drinks. Food is the main source of energy and of nutrition for animals, and is usually of animal or plant origin. Humans are omnivorous animals that can consume both plant and animal products. We changed from gatherers to hunter gatherers. After the experience of the ice age it is probable that humans wanted to create some feeling of security by controlling what plants were growing and which animals were available. This led to agriculture, which has continually improved and altered the way in which food is obtained. A selection of different complementary foods eaten together comprises a meal. People often choose to eat meals together with other family members or friends and this is seen as an important social occasion. Food eaten in smaller quantities between meals is regarded as snack food. The number of meals in a day, their size, composition, when and how they are prepared and eaten vary greatly around the world. This is greatly dependent on the local climate, ecology, economy, cultural traditions and industrialisation.
