The Crusades originated as expeditions to deliver the Holy Land from Muslim rule, with participants wearing crosses as badges to signify their vow. Over time, the word "crusade" came to refer more broadly to any wars undertaken in pursuit of a religious cause. The document provides background on the origins and evolving meaning of the term "Crusades" in reference to the religious military expeditions between European Christians and Middle Eastern Muslims in the 11th-13th centuries.