With alternative therapies is meant all therapies and medicines for which is no scientific evidence of how it works. There are many types of alternative therapies.
You have the manual therapies, which focus at the joints and muscles. By moving the body parts around the joint in a certain way, can the pain go away and the movement of the joints can improved.
In manual alternative therapies such as osteopathy and chiropractic is believed that all problems are caused because the body is no longer in balance. By manipulating (twisting, cracking) would get everything back into balance. The body will repair itself.
These are holistic therapies and holistic therapists often advise against surgery or medication. Instead they rely on prayer, meditation and homeopathic medicine made from herbs and vitamins.
It also says it is a "whole person" treatment. They believe that the spirit, soul and body are connected to a natural energy of the universe, called Chi. So they say that spirit, soul and body is one. The Bible tells us something different:
23 And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ. 1 Thess. 5:23
Some alternative therapists believe that a particular body part contains a kind of map of the whole body. So that every organ in the human body has a position on that "map".
An Iridologist takes a look in the eye and sees exactly which body part is not functioning. With reflexology they massage the corresponding spot in the foot and the pain will disappear. By ear-acupuncture they stick a needle in your ear at the corresponding place.
Others use the healing powers of herbs and botanicals, such as homeopathy, aromatherapy and Bach Flower Therapy.
What all these therapies have in common is that they often do some work, but usually the symptoms (worse) come back. The biggest danger is that the source is occult. My advice: Do not do it!