A common market organisation is a set of measures that enables the European Union to manage, to a greater or lesser degree, the markets for agricultural products within its own territory. Markets are managed by altering the supply and demand for agricultural products from the situation that would pertain if markets were entirely "free". The purpose of market management is to stabilise markets (in terms of quantity offered and purchased and the price at which transactions take place) and thus to ensure, on the one hand, that farmers do not suffer from excessively low prices and, on the other, that consumers have a secure supply of food at reasonable prices.Until 2007, the European Union operated 21 common market organisations which together covered around 90% of the output of farms.In a bid, however, to make things simpler, the European Union has amalgamated these 21 common market organisations into a single set, known as the single common market organisation.