In short, agribusiness is the business of farming. However, the word is a loaded term, especially among critics of corporate farming. For people who view large-scale commercial farming negatively, agribusiness is the antithesis of traditional small-scale family farms. For people involved in it, of course, the word is simply a convenient shorthand for saying that one is in the business of agriculture.
Agribusiness includes the production, processing, and supply of agricultural goods that range from lettuce to corn syrup. Companies may focus on things like cut flowers, fresh vegetables, or byproducts of farming such as fuels derived from farm waste. Agribusiness also encompasses farming equipment, machinery, chemicals, suppliers, and personnel. Several large companies control the bulk of the share of business, especially in the United States; this has been a cause for criticism among people who are concerned about monopolies and price fixing.
Several things characterize agribusiness, differentiating it very distinctively from family farming. The first is the scale, which is typically quite large. The second is considerable vertical and horizontal integration. For example, a company might own a facility that processes frozen vegetables, along with a controlling share in farms which produce these vegetables and companies which provide personnel to harvest and transport them. Agribusiness is also distinguished by being run like a true business, with administrators rather than farmers at the helm of companies in the agriculture business.