Open Interest (OI) is the total number of outstanding derivative contracts (futures or options) that have not been settled or closed.
Open Interest represents the total active positions in a derivatives market at a given time. It increases when new contracts are created and decreases when contracts are closed or expired.
It is widely used in markets like derivatives trading on the National Stock Exchange and Bombay Stock Exchange, regulated by the Securities and Exchange Board of India.
"If 1,000 futures contracts are open and not yet closed, the open interest is 1,000."