Massage is the treatment and practice of soft tissue manipulation with physical, functional, and in some cases psychological purposes and goals. The word comes from the French massage "friction of kneading," or from Arabic massa meaning "to touch, feel or handle" or from Latin massa meaning "mass, dough". (In distinction the ancient Greek word for massage was anatripsis, and the Latin was frictio.) An older etymology may even have been the Hebrew me-sakj "to anoint with oil."
Massage involves acting on and manipulating the client's body with pressure (structured, unstructured, stationary, and/or moving), tension, motion, or vibration done manually or with mechanical aids. Target tissues may include muscles, tendons, ligaments, skin, joints, or other connective tissue, as well as lymphatic vessels, and/or organs of the gastrointestinal system. Massage can be applied with the hands, fingers, elbows, forearm, and feet. There are over eighty different massage modalities. The most cited reasons for introducing massage have been client demand and perceived clinical effectiveness. 
In professional settings massage involves the client being treated while lying on a massage table, sitting in a massage chair, or lying on a mat on the floor. The massage subject may be fully or partly unclothed. Parts of the body may be covered with towels or sheets.

Ancient and medieval times
Writings on massage have been found in many ancient civilizations including Rome, Greece, Japan, China, Egypt, Mesopotamia and India. A biblical reference from c.493 BC documents daily massage with olive oil and myrrh as a part of the beauty regimen of the wives of Xerxes. (Esther, 2:9-12) Hippocrates wrote in 460 BC that "The physician must be experienced in many things, but assuredly in rubbing." The ancient Chinese book called Huangdi Neijing by the Yellow Emperor recommended "massage of skin and flesh." The technique of massage abortion, involving the application of pressure to the pregnant abdomen, has been practiced in Southeast Asia for centuries. One of the bas reliefs decorating the temple of Angkor Wat in Cambodia, dated circa 1150, depicts a demon performing such an abortion upon a woman who has been sent to the underworld. This is believed to be the oldest known visual representation of abortion. In Romania some illnesses were treated by a massage in which the client was trodden on by a tame bear. 

Massage methods
Massage can be performed by a massage therapist, or by other health care professionals, such as chiropractors, osteopaths, athletic trainers, and/or physical therapists. Massage therapists work in a variety of medical and recreational settings and may travel to private residences or businesses. Contraindications to massage include deep vein thrombosis, bleeding disorders or taking blood thinners such as Warfarin, damaged blood vessels, weakened bones from cancer, osteoporosis, or fractures, and fever. 

Acupressure
Acupressure (a blend of "acupuncture" and "pressure") is a traditional Chinese medicine (TCM) technique derived from acupuncture. In acupressure physical pressure is applied to acupuncture points by the hand, elbow, or with various devices.

Ashiatsu
Ashiatsu massage is an eastern (oriental) born therapy that is designed to rebalance your physical being by rebalancing your energy field ("shi" meaning finger and "astsu" meaning pressure.) Ashiatsu uses pressure applied with thumbs, fingers and palms to specific pressure points of the body. It also uses techniques such as rolling, brushing, vibrating, grasping and in one particular technique developed by Suzuki Yamamoto, pressure is applied with the feet on the persons back, legs and feet (special set up is required for the "foot" Ashiatsu.)

Bowen therapy
Bowen technique involves a rolling movement over fascia, muscles, ligaments, tendons and joints. It is said not to involve deep or prolonged contact with muscle tissues as in most kinds of massage, but claims to relieve muscle tensions and strains and to restore normal lymphatic flow. It is based on practices developed by Australian Tom Bowen. 

Shiatsu
Shiatsu is a form of Japanese massage that uses thumb pressure and works along the same energy meridians as acupressure and incorporates stretching.

Stone massage
A stone massage uses cold or water-heated stones to apply pressure and heat to the body. Stones coated in oil can also be used by the therapist delivering various massaging strokes.

Structural Integration
Structural Integration's aim is to unwind the strain patterns residing in your body's myofascial system, restoring it to its natural balance, alignment, length, and ease. This is accomplished by deep, slow, fascial and myofascial manipulation, coupled with movement re-education. Various brands of Structural Integration are Kinesis Myofascial Integration and rolfing

Swedish massage
Swedish massage uses five styles of long, flowing strokes to massage. The five basic strokes are effleurage (light touch), petrissage (kneading), tapotement (rhythmic tapping), friction (compression), and vibration. Swedish massage has shown to be helpful in reducing pain, joint stiffness, and improving function in patients with osteoarthritis of the knee over a period of eight weeks. The development of Swedish massage is credited to Per Henrik Ling though the Dutch practitioner Johan Georg Mezger adopted the French names to denote the basic strokes.

Thai massage
Known in Thailand as (Nuat phaen boran, , meaning "ancient/traditional massage", Thai massage originated in India and is based on ayurveda and yoga. It was believed that the massage art was brought over to Thailand by Shivago Komarpaj over 2500 years ago. The technique combines massage with yoga-like positions during the course of the massage; the northern style emphasizes stretching while the southern style emphasizes acupressure.

Traditional Chinese massage
Two types of traditional Chinese massage exist - Tui na  which focusses on pushing, stretching and kneading the muscle and Zhi Ya  which focuses on pinching and pressing at acupressure points. Both are based on principles from Traditional Chinese Medicine.

Trager Approach
The Trager approach combines movement, massage and education.

Trigger point therapy
Also called a pressure point massage, this involves stimulating hypothetical trigger point that may refer pain sensations to other parts of the body. Manual pressure is applied to these points. Trigger point therapy was founded by Janet G. Travell and David Simons.

Visceral manipulation
Methods such as Visceral Manipulation have been part of the medicinal cultures in Europe and Asia since prerecorded times. Indeed, manual manipulation of the internal organs has long been a component of some therapeutic systems in Oriental medicine. So it's no surprise that practitioners in many parts of the world have incorporated manipulations designed to work with the internal organs and their functions.

Benefits of Massage
Peer-reviewed medical research has shown that the benefits of massage include pain relief, reduced trait anxiety and depression, and temporarily reduced blood pressure, heart rate, and state anxiety. Theories behind what massage might do include blocking nociception (gate control theory), activating the parasympathetic nervous system which may stimulate the release of endorphins and serotonin, preventing fibrosis or scar tissue, increasing the flow of lymph, and improving sleep but such effects are yet to be supported by well designed clinical studies.
Massage is hindered from reaching the gold standard of scientific research which includes placebo-controlled and double blind clinical trials. Developing a "sham" manual therapy for massage would be difficult since even light touch massage could not be assumed to be completely devoid of effects on the subject. It would also be difficult to find a subject that would not notice that they were getting less of a massage and it would be impossible to blind the therapist. Massage can employ randomized controlled trials which are published in peer reviewed medical journals. This type of study could increase the credibility of the profession because it displays that purported therapeutic effects are reproducible. 

Single dose effects
Pain relief: Relief from pain due to musculoskeletal injuries and other causes is cited as a major benefit of massage. In one study, cancer patients self-reported symptomatic relief of pain. This study, however, did not include a no treatment or placebo control group so these effect may be due to the placebo effect or regression towards the mean. Massage can also relieve tension headaches. Acupressure or pressure point massage may be more beneficial than classic Swedish massage in relieving back pain. However, a meta-study conducted by scientists at the University of Illinois at Urbana-Champaign failed to find a statistically significant reduction in pain immediately following treatment. 
State anxiety: Massage has been shown to reduce state anxiety, a transient measure of anxiety in a given situation. 
Blood pressure and heart rate: Massage has been shown to reduce blood pressure and heart rate as temporary effects. Attention: After massage, EEG patterns indicate enhanced performance and alertness on mathematical computations, with the effects perhaps being mediated by decreased stress hormones. 
Other: Massage also stimulates the immune system by increasing peripheral blood lymphocytes (PBLs). However, this immune system effect is only observed in aromatherapy massage, which includes sweet almond oil, lavender oil, cypress oil, and sweet marjoram oil. It is unclear whether this effect persists over the long term.

Multiple dose effects
Pain relief: When combined with education and exercises, massage might help sub-acute, chronic, non-specific low back pain. Furthermore, massage has been shown to reduce pain experienced in the days or weeks after treatment. 
Trait anxiety: Massage has been shown to reduce trait anxiety; a person's general susceptibility to anxiety. 
Depression: Massage has been shown to reduce subclinical depression. 
Diseases: Massage, involving stretching, has been shown to help with spastic diplegia resulting from Cerebral palsy in a small pilot study. The researchers warn that these results should "be viewed with caution until a double-blind controlled trial can be conducted".
Massage has been used in an effort to improve symptoms, disease progression, and quality of life in HIV patients, however, this treatment is not scientifically supported.