Clientelism is the exchange of goods and services for political support, often involving an implicit or explicit quid-pro-quo. It is a political system at the heart of which is an asymmetric relationship between groups of political actors described as patrons and clients and political parties. Richard Graham has defined clientelism as a set of actions based on the principle take there, give here, with the practice allowing both clients and patrons to gain advantage from the other's support. Moreover, clientelism is typified by "exchange systems where voters trade political support for various outputs of the public decision-making process."
The origin of the practice has been traced to ancient Rome. Here tionships between the patron (patronus) and client (cliens) were seen as crucial to understanding the political process. While the obligations between these were mutual, the key point is they were hierarchical. These relationships might be best viewed not as an entity but rather as a network (clientela), with the patronus himself perhaps being obligated to someone of greater power, and the cliens perhaps having more than one patron. These extensions increase the possibilities of conflicting interests arising. While the familia was the basic unit underlying Roman society, the interlocking networks (clientela) acted as restrictions on their autonomy but allowed a more complex society to develop. Historians of the late medieval period evolved the concept into bastard feudalism. There is, as is usual, ambiguity in the use of political terminology and the terms "clientelism," the "patron-client relationship," "patronage" and the political machine are sometimes used to describe similar or related concepts.
The patron/client system can be defined as a mutual arrangement between a person that has authority, social status, wealth, or some other personal resource (patron) and another who benefits from their support or influence. The patron provides selective access to goods and opportunities, and place themselves or their support in positions from which they can divert resources and services in their favor. Their partners-clients- are expected to buy support, and in some cases, votes. What the patrons see is the low-income and limited assets the client has and uses that resource, which is in great abundance: time, a vote, and insertion into networks of other potential supporters whom they can influence.