Agriculture is one of the oldest and most important industries. In 2016, total agricultural production was valued at 3.7 trillion USD or around 4.9 percent of world GDP. Agriculture tends to represent a higher percentage of GDP for poorer countries compared to rich. Two-thirds of total production came from crops while the rest was from livestock. The largest producers of crops were China (35 percent), India (11 percent), and USA (8 percent). The largest producers of livestock were China (29 percent), USA (11 percent), and India (7 percent). The largest agricultural exporters in 2016 were the USA (9.3 percent), China (7.4 percent), Germany (5.9 percent), and the Netherlands (5.2 percent). The largest importers were the USA (10.1 percent), China (7.45 percent), and Germany (6.7 percent). The domestication of crops and animals began around 12,000 years ago. Wheat was first farmed in the Middle East. Other key crops were then introduced in several other key sites around the world including Northern China, southern Mexico, and Peru. Despite its long history however, the practice and technology of agriculture changed little over time. In 18th century Britain, the first modern agricultural revolution began. Farmers started to switch to higher yield crops like barley and wheat. A greater percentage of land was utilised with turnips and clover replacing fallow ground in crop rotations. Adding legumes to crop rotations also increased the nitrogen in the soil leading to higher yields for following crops. Enclosed pastures also allowed the rise of selective breeding. In the 19th century a second revolution began with the advent of chemical fertilisers, the rise of cooperative movements, and duty-free national markets. After WW2, widespread mechanisation and modern irrigation increased labour productivity and yields. The 20th century also saw the discovery of DNA and the development of selective breeding for beneficial crop mutations. Newer advances include gene editing, the use of big data, precision farming with the use of GPS, and bio-fuels. There has also been a movement towards environmentally sustainable practices due to challenges such as soil degradation and pest resistance to pesticides. The spectre of climate change is also driving change. In terms of political economy, the sudden rise in food prices in 2007-08 pointed to the ongoing work needed to help developing countries improve agricultural practices particularly as the world’s population continues to increase.