Cascara is a Spanish word that means husk. It's very interesting, because cascara reminds us that coffee is a fruit, and beans are coffee seeds, to be more precise.
In recent years, cascara became popular, and it has many different uses. Mostly, it's great to brew infusions with hot water, but researchers have found plenty of applications as a food ingredient and to develop nutritional supplements, among others.
You can check a recent publication about this, and the importance of using coffee by-products to our advantage: