Agriculture (a term which encompasses farming) is the process of producing food, feed, fiber and other goods by the systematic raising of plants and animals.

Agri is from Latin ager, meaning "a field", and culture is from Latin cultura, meaning "cultivation" in the strict sense of tillage of the soil. A literal reading of the English word yields: tillage of the soil of a field. In modern usage, the word Agriculture covers all activities essential to food/feed/fiber production, including all techniques for raising and processing livestock. Agriculture is also short for the study of the practice of agriculture – more formally known as agricultural science. The history of agriculture is closely linked to human history, and agricultural developments have been crucial factors in social change, including the specialization of human activity.

Farming refers to a wide range agricultural production work, covering a large spectrum of operation scales (acerage, output, etc), practices, and commercial inclination. At one end of this spectrum, the subsistence farmer farms a small area with limited resource inputs, and produces only enough food to meet the needs of his/her family.

At the other end of the spectrum is commercial intensive agriculture, including industrial agriculture. Such farming involves large fields and/or numbers of animals, large resource inputs (pesticides, and fertilizers, etc.), and a high level of mechanization. These operations generally attempt to maximize financial income from produce or livestock.

Modern agriculture extends well beyond the traditional production of food for humans and animal feeds. Other agricultural production goods include cut flowers, ornamental and nursery plants, timber, fertilizers, animal hides, leather, industrial chemicals (starch, sugar, ethanol, alcohols and plastics), fibers (cotton, wool, hemp, and flax), fuels (methane from biomass, biodiesel) and both legal and illegal drugs (biopharmaceuticals, tobacco, marijuana, opium, cocaine).

The 20th Century saw massive changes in agricultural practice, particularly in agricultural chemistry. Agricultural chemistry includes the application of chemical fertilizer, chemical insecticides (see Pest control), and chemical fungicides, soil makeup, analysis of agricultural products, and nutritional needs of farm animals. Beginning in the Western world, the green revolution spread many of these changes to farms throughout the world, with varying success.

Other recent changes in agriculture include hydroponics, plant breeding, hybridization, gene manipulation, better management of soil nutrients, and improved weed control. Genetic engineering has yielded crops which have capabilities beyond those of naturally occurring plants, such as higher yields and disease resistance. Modified seeds germinate faster, and thus can be grown in an extended growing area. Genetic engineering of plants has proven controversial, particularly in the case of herbicide-resistant plants.

Engineers may develop plans for irrigation, drainage, conservation and sanitary engineering, particularly important in normally arid areas which rely upon constant irrigation, and on large scale farms.

The packing, processing, and marketing of agricultural products are closely related activities also influenced by science. Methods of quick-freezing and dehydration have increased the markets for farm products.

Animals, including horses, mules, oxen, camels, llamas, alpacas, and dogs, are often used to cultivate fields, harvest crops and transport farm products to markets. Animal husbandry means breeding and raising animals for meat or to harvest animal products (like milk, eggs, or wool) on a continual basis. Mechanization has enormously increased farm efficiency and productivity in Western agriculture.

Airplanes, helicopters, trucks and tractors are used in Western agriculture for seeding, spraying operations for insect and disease control, Aerial topdressing and transporting perishable products. Radio and television disseminate vital weather reports and other information such as market reports that concern farmers. Computers have become an essential tool for farm management.

According to the National Academy of Engineering in the US, agricultural mechanization is one of the 20 greatest engineering achievements of the 20th century. Early in the century, it took one American farmer to produce food for 2.5 people. Today, due to advances in agricultural technology, a single farmer can feed over 130 people. This comes at a cost, however. A large energy input, often from fossil fuel, are required to maintain such high levels of output.

In recent years, some aspects of intensive industrial agriculture have been the subject of increasing discussion. The widening sphere of influence held by large seed and chemical companies, meat packers and food processors has been a source of concern both within the farming community and for the general public. Another issue is the type of feed given to some animals that can cause Bovine Spongiform Encephalopathy in cattle. There has also been concern because of the disastrous effect that intensive agriculture has on the environment. In the US, for example, fertilizer has been running off into the Mississippi for years and has caused a dead spot in the Gulf of Mexico, where the Mississippi empties. Intensive agriculture also depletes the fertility of the land over time, potentially leading to Desertification.

The patent protection given to companies that develop new types of seed using genetic engineering has allowed seed to be licensed to farmers in much the same way that computer software is licensed to users. This has changed the balance of power in favor of the seed companies, allowing them to dictate terms and conditions previously unheard of. The Indian activist and scientiest Vandana Shiva argues that these companies are guilty of biopiracy.

Soil conservation and nutrient management have been important concerns since the 1950s, with the best farmers taking a stewardship role with the land they operate. However, increasing contamination of waterways and wetlands by nutrients like nitrogen and phosphorus are of concern in many countries.

Increasing consumer awareness of agricultural issues has led to the rise of community-supported agriculture, local food movement, Slow Food, and commercial organic farming.