The primary ingredient for traditional Greek tzatziki is yogurt, specifically thick, strained Greek yogurt. This ingredient gives tzatziki its creamy texture and tangy flavor. The yogurt is typically mixed with grated cucumber, garlic, olive oil, lemon juice, and various herbs such as dill or mint. Tzatziki is commonly served as a dip or sauce, often accompanying grilled meats, pita bread, or vegetables, and is a staple in Greek cuisine, balancing flavors and adding a refreshing element to many dishes.