A farmer (also called an agriculturer) is a person engaged in agriculture, raising living organisms for food or raw materials. The term usually applies to people who do some combination of raising field crops, orchards, vineyards, poultry, or other livestock. A farmer might own the farmed land or might work as a labourer on land owned by others, but in advanced economies, a farmer is usually a farm owner, while employees of the farm are farm workers, farmhands, etc.

Source: Wikipedia (Farmer)

Further reading:

Each farmer is typically involved in one or more of these economic activities (ISIC):

The functions of government (COFOG) that are specifically relevant for farmers and farm workers are (COFOG):

A farmer typically relies on suppliers from several of these economic activities (ISIC):

A farmer typically sells his or her produce to customers in these economic activities (ISIC):