What is a Trigger Point?
A trigger point is a taut band of skeletal muscle inside a muscle group. Trigger points are tender to the touch and can refer pain to distant body parts. There may be regional, persistent pain resulting in a decreased range of motion in the affected muscles. Trigger points feel like little marbles or knots just under your skin. When pressing on trigger points, many people feel no pain or discomfort. Sometimes, trigger points become very sensitive, and some people feel significant pain in areas where they have trigger points. 
What is Trigger Point Therapy?
Trigger Point Therapy is a soft-tissue treatment that helps release tense, painful knots in your muscles and fascia (web of connective tissue). Components of trigger point therapy may include sustained pressure, posture and movement correction, electrical stimulation, dry needling, and massage.  Myofascial Pain Syndrome refers to regional pain of soft tissue origin. It is associated with muscle tenderness that arises from TrPs, focal points of tenderness a few millimeters in diameter, found at multiple sites in a muscle and the fascia of muscle tissue.
What Causes Trigger Points?
There are a number of factors that bring about Trigger Points: aging, injury sustained by a fall, stress or birth trauma, Lack of exercise, bad posture, weightlifting, chronic stress condition, vitamin deficiencies, sleep disturbance, joint problems, and hypermobility.
How Trigger Point Therapy Works
Trigger Point Therapy has a unique process with which it is carried out. This can help improve circulation and normal movement of your muscles.  Other treatments for trigger points include Exercises to help change your posture and the way your body moves, Kinesiology taping, Therapeutic modalities like ultrasound and electrical stimulation, Dry needling, Acupuncture, Laser therapy, Prolotherapy (injecting solutions in the region of TrPs: lidocaine, glycerine, phenol, etc.)
In conclusion, although no laboratory test or imaging technique has been established for diagnosing TrPs, Trigger Point Therapy is an established field that holds a lot of promise. With it, Trigger Points can be completely healed and medically catered for, and all deficiencies can be painlessly eradicated.
Melzack R, et al., Trigger points and acupuncture points for pain: correlations and implications. Pain 1977; 3:3-23
Sola A. et al Myofascial pain syndromes. Neurology 1956; 6:91-96