Technically a white-wine vinegar, true balsamic vinegar becomes rich and dark through a long process that begins with fresh white wine that is cooked down to a thick, syrupy consistency and then fermented and aged in a succession of special wooden casks for a minimum of twelve years. Pungent, exotic, and slightly sweet, true balsamic vinegar should only be savored in its purest form, never heated or mixed with other ingredients, but judiciously drizzled on food or sipped as you would a fine liqueur. Commercial balsamic vinegar is actually a red-wine vinegar fortified with concentrated grape juice and sometimes caramelized sugar that's intended to imitate true balsamic vinegar. While this widely available balsamic vinegar may not compare to the real thing, some brands are valued for their dark, slightly sweet, pungent characteristics. White balsamic vinegar is another loose interpretation of traditional balsamic.
Cider vinegar is milder and sweeter than most wine vinegars.
The best are unfiltered and unpasteurized. Good cider vinegar is slightly cloudy, like fresh cider, and has a fruity, apple flavor. White, with its pale, golden color and delicate flavor, is by far the most popular. Japanese rice vinegar is milder and sweeter than the Chinese, which tends to be more acidic and sharp. Their stronger flavors make them less versatile than other vinegars.