Apple cider vinegar is made from fermented apple juice, it is used for food preservation, marinades, vinaigrettes salad dressings. It has a sour taste, and can be used to make homemade cleaning products.
ACV is made from crushing apples and extracting the juice, bacteria and yeast are then aded to kickstart the fermentation process which converts the sugars into alcohol. There is a second fermentation, which then turns the alcohol into vinegar by acetic acid-forming bacteria. It can be used as a leavening agent in recipes, when mixed with baking soda, creating a chemical reaction which produces carbon dioxide which helps lift the batter.