Vinegar is a liquid made of acetic acid and water. The acetic acid is produced during the fermentation of barley (malt vinegar), grapes (wine vinegar), or rice (rice vinegar). While the different types of vinegar may generally be used interchangeably, there are some uses for which one or another is most commonly used. For example, rice vinegar is always used in preparing sushi, while malt vinegar is the preferred seasoning for fish & chips (see deep-frying), and wine vinegar is most commonly used in cooking or salad dressings. Any vinegar may be used for pickling various vegetables (such as cubecumbers, which when pickled are simply called "pickles"; or pickled beets, ginger, peppers, etc.) or as a table seasoning for various vegetables. Historically, pickling has often been used as a means of preserving food for extended periods, due to the lack of refrigeration. Vinegar may also be used in making various sauces, such as ketchup, barbecue sauce, or steak sauce.