Reform and Opening Up is one of the most important events in modern Chinese history.
Tips
history
改革开放 was initiated by Deng Xiaoping in 1978. 改革 (reform) refers to domestic economic restructuring, while 开放 (opening up) refers to opening China to foreign trade and investment.
culture
This phrase is essential knowledge for HSK and any discussion of modern China. It's often used as a time marker: 改革开放以来 (since Reform and Opening Up).