It's a term that has been made famous by the eurozone crisis, and it refers loosely to the international inspectors from the European Union and the International Monetary Fund who have been tasked with implementing austerity and reform in Greece, and other countries that have received international bailouts over the last few years.
Now the new Greek government says it wants nothing to do with the troika in its current form, and it won't extend its bailout when it expires at the end of the month.
Greece and the future of the troika are high on the agenda for a series of meetings over the next few days, including a European summit on Thursday. The BBC's Europe correspondent Chris Morris reports.
This segment aired on February 10, 2015.