Short answers, pulled from the story.
Subsistence agriculture is farming in which crops are grown on smallholdings primarily to meet the needs of the farmer and their family. Sociology professor Tony Waters defines subsistence peasants as "people who grow what they eat, build their own houses, and live without regularly making purchases in the marketplace."
In 2015, approximately 2 billion people, slightly more than 25% of the world's population, were living as smallholder farmers in 500 million households across developing nations. Each household worked less than 2 hectares, roughly 5 acres, of land.
The main types are shifting agriculture, sedentary farming, nomadic herding, and intensive subsistence farming. Shifting agriculture involves clearing forest by burning, farming for two to three years, then moving to a new plot while the original land recovers. Intensive subsistence farming works small plots with high labor input, sometimes creating terraced rice paddies on steep hillsides.
Subsistence agriculture was the dominant farming mode in Europe and North America until around 1800. It had largely disappeared from Europe by the start of the twentieth century. In North America, decline accelerated with the movement of sharecroppers and tenant farmers out of the American South and Midwest during the 1930s and 1940s.
Extreme temperatures linked to climate change are lowering yields of cereal crops including wheat, oats, and maize. Dryland subsistence farmers who rely on rain-fed farming are especially vulnerable. Some farmers have sold livestock and consumed seeds saved for planting to cope with losses, which reduces their capacity to farm in following seasons.
Ethiopia and parts of Asia have close to 90% of their farmers working as smallholders. India has 80% smallholder farmers, and China accounts for around half of all farms in the world, with approximately 98% of Chinese farmers working small holdings.