There are currently four takaful models operated worldwide which apply to several forms of contract governing the relationship between participants and the takaful operator. The most widely practised models are mudarabah and wakalah. Some takaful operators adopt a hybrid model either combining mudarabah and wakalah or wakalah with waqf model or even mudarabah and waqf. However, the most commonly used contracts are mudarabah (profit-sharing), wakalah (agency) and waqf (endowment). For further details see: Islamic Financial System; Principles and Operations.