© Denzil Green
Cider Vinegar, sometimes called by its full name “Apple Cider Vinegar”, is a light amber coloured, inexpensive vinegar made from fermented apples. 
It has a real tang, which is a bit much for delicate vinaigrettes or sauces, but it holds its own well against stronger tastes in chutneys and marinades.
It is the most popular vinegar in the United States, and ties with malted vinegar in popularity in Canada particularly for use on chips (aka French Fries.) It is also popular in other English-speaking countries such as the UK, Australia, New Zealand, etc.
In Canada, by law, cider vinegar must be made from apple; it cannot be just vinegar that has had apple flavour added to it. 
The average pH of Apple Cider Vinegar is around 3.10. [2a]
Cider Vinegar gives a nice flavour in pickling, but owing to its colour may darken light fruit or vegetables a bit (but the coloration does not affect the flavour.) Use in chutneys, marinades, pickled onions, stronger salad dressings, etc.
White vinegar (if making pickles); malt vinegar.
Apple Cider Vinegar has no health benefits
Claims that apple cider vinegar has any medicinal benefits are just that — claims, and anecdotes, with no scientific evidence to back them. In other words, myth. The American Food and Drug Administration (FDA) allows no health or medicinal benefit claims in relation to cider vinegar. See the case of what happened to “Jogging in a Jug”, an apple cider beverage which did make those claims.
There are various magic ways, reputedly, in which cider vinegar is supposed to help you. The claims include that it normalizes your body’s acid/alkaline balance; that it’s rich in minerals, enzymes and vitamins; that the pectin in it helps your bowels; that phosphorus in it prevents bad bacteria from forming in your body; that unpasteurized, raw cider vinegar has a magic vitalism  to it.
The facts are that your stomach is so acidic, no food can change its acidity. In fact, your body operates within a narrow pH range that you would not even want anything to be affecting it. “Dietary modification cannot change the acidity of any part of your body except your urine. Your bloodstream and organs control acidity in a very narrow range. Anything that changed acidity in your body would make you very sick and could even kill you.” 
Cider Vinegar is not rich in minerals, enzymes and vitamins; in fact, it’s quite the opposite. A look at its components shows you it’s quite empty of anything that could be beneficial in that regard:
1 tablespoon apple cider vinegar: 1g carbohydrate, 15 mg of potassium. No fibre, vitamins or amino acids. negligible amounts of calcium (1mg), copper, iron, magnesium, manganese, phosphorus and sodium. 
Cider Vinegar contains no pectin; it contains a negligible amount of phosphorus (1 mg); and vitalism is essentially a spiritual belief that food has some kind of undetectable spiritual energy to it that you only know is there because someone said they detected it.
Despite this, there is a big cult following now around the reputed health benefits of raw, unprocessed (i.e. non-distilled) Cider Vinegar, often in the form of pills. But it is myth and junk science.
There is no conspiracy by the American Food and Drug Administration colluding with drug companies to deprive people of an inexpensive, natural remedy. The FDA is just doing its job of preventing people from selling you snake oil. There have been multiple controlled clinical case studies that show no benefit, at all. Anecdotes about someone’s grandmother taking Apple Cider Vinegar, along with claims and testimonials, are what is called “experiential evidence”, which is often what junk science is based on.
If you have a medical condition, do not place any stock in Apple Cider Vinegar doing anything for you. Enjoy the taste of Apple Cider vinegar on your fries and in your salad dressings, but enjoy it for what it is, a tasty vinegar.
The Egyptians made Apple Cider Vinegar.
Some think the idea of the health benefits of apple cider vinegar originated with a Dr DeForest Clinton Jarvis (March 15, 1881 – August 18, 1966) of Vermont. He popularized his ideas in his 1958 book, “Folk Medicine: A Vermont Doctor’s Guide to Good Health.” His ideas on cider vinegar in particular were denounced as quackery even at the time.
 What is used in fact is often the “pomace” of apples: what’s left of an apple after it has been pressed or put through a spin extraction process to make apple juice or cider.
 “B.19.006. [S]. Cider Vinegar or Apple Vinegar shall be vinegar made from the liquid expressed from whole apples, apple parts or apple culls and may contain caramel.” — Canada. Food and Drug Regulations Consolidation. C.R.C., c. 870. Division 19. 7 November 2014. Page 755.
[2a] FDA. Approximate pH of Foods and Food Products. April 2007. Page 12. Accessed August 2015 at http://foodscience.caes.uga.edu/extension/documents/FDAapproximatepHoffoodslacf-phs.pdf)
 Vitalism is reputed to be: “a vital life force energy that differs from the laws of physics, chemistry or biology and cannot be seen, detected or measured by science… Today’s practitioners often refer to it as a type of bioenergy field or holistic essence… Vitalism is also conferred to our foods and environment, as certain whole, natural foods are believed to have more vital life energy, live enzymes and an ability to heal and prevent disease…. like other beliefs surrounding vitalism, they “work” primarily through placebo and nocebo effects.” Szwarc, Sandy. Junkfood Science: The essence of wellness. 10 April 2007. Retrieved November 2012 from http://junkfoodscience.blogspot.ca/2007/04/essence-of-wellness.html
 Dr. Gabe Mirkin, M.D. Georgetown University School of Medicine. Acid/Alkaline Theory of Disease Is Nonsense. Retrieved November 2012 from http://www.quackwatch.org/01QuackeryRelatedTopics/DSH/coral2.html
 Fontenot, Beth. The sour truth about apple cider vinegar – evaluation of therapeutic use. Nutrition Forum, Nov-Dec, 1997.
Szwarc, Sandy. Junkfood Science: Houston, we have a problem — Apple cider vinegar remedies. 3 April 2008. Retrieved from http://junkfoodscience.blogspot.ca/2008/04/houston-we-have-problem-apple-cider.html