'Agriculture', which encompasses 'farming', is the process of producing food, feed, fiber and other goods by the systematic raising of plants and animals. Agricultural developments have been crucial factors in social change, including the specialization of human activity. 42% of the world's laborers are employed in agriculture, making it by far the most common occupation. However, agricultural production accounts for less than 5% of the Gross World Product (an aggregate of all Gross Domestic Products). Basic topics in agriculture include: