A marinade is a flavorful liquid that you soak foods in before cooking. Marinades typically use an acidic ingredient, such as lemon juice or vinegar, to help tenderize the meat and carry the flavors into the foods. They also help keep your food moist when you cook them. Baked or grilled recipes frequently benefit from this process. You can add your favorite herbs, spices and condiments to a marinade to customize it into the perfect recipe for you.