In the foreign exchange market and international finance, a world currency or global currency refers to a currency in which the vast majority of international transactions take place and which serves as the world's primary reserve currency. In March 2009, as a result of the global economic crisis, China and Russia have pressed for urgent consideration of a global currency and a UN panel has proposed greatly expanding the IMF's SDRs or Special Drawing Rights.

A world currency is at one extreme of a conceptual spectrum that has local currency at the other extreme.

Currencies have many forms depending on several properties: type of issuance, type of issuer and type of backing. The particular configuration of those properties leads to different types of money. The pros and cons of a currency are strongly influenced by the type proposed. Consider, for example, the properties of a complementary currency.