Entryism is a political tactic in which an organisation or group enters a larger organisation in an attempt to gain recruits, gain influence or to take control of the larger organisations' structure. This technique is commonly used by groups from the far left or right of the political spectrum to enter more centrist institutions. This is experienced more frequently in arenas where opportunities for political activity at the fringes is limited, such as two party/majoritarian systems rather than in multiparty/proportional systems where the cost of entry into the political system is lower. Organisations which are the subject of entryism often react by attempting either to marginalise or expel the pratagonists.