What is a very tart red berry used for sauce or juice?

A very tart red berry commonly used for sauce or juice is the cranberry. Cranberries are known for their sharp, tangy flavor and are often sweetened when made into sauces or beverages. They are rich in antioxidants and are popular during the holiday season, particularly in dishes like cranberry sauce. Additionally, they can be enjoyed in various forms, including juices and jams.