Who were the two opponents fighting in the crusades?

The primary opponents in the Crusades were the Christian forces from Europe, led by various kings and knights, and the Muslim armies, notably those led by leaders such as Saladin. The Crusades were a series of religious wars initiated by Christians to reclaim the Holy Land from Muslim control, particularly Jerusalem. Over the centuries, various factions and leaders emerged on both sides, but the overarching conflict was between these two religious groups.