A farmer is someone who works under the umbrella of agriculture, producing a variety of food products for human and animal consumption. There are several kinds of farmers ranging from farmers who raise animals to farmers who grow crops.
There is a quote that is very accurate when describing a farmer - "Farmers farm for the love of farming. They love to watch and nurture the growth of plants. They love to live in the presence of animals. They love to work outdoors. They love the weather, maybe even when it is making them miserable." - Wendell Berry.
farmer's main goal is to produce a good crop and/or healthy animals in order to make a living and to feed the population. Farmers are responsible for all crops and livestock that are needed for us to survive. Without food, the world would slowly die