Therapy
A therapy or medical treatment (Both words, "Treatment" and "Therapy" are often abbreviated tx, Tx, or Tx) is the attempted remediation of a health problem, usually following a medical diagnosis.
As a rule, each therapy has indications and contraindications.  There are many different types of therapy.  Not all therapies are effective.  Many therapies can produce unwanted adverse effects.
Medical treatment and therapy are generally considered synonyms.  However,  in the context of mental health, the term therapy may refer specifically to psychotherapy.

History
Before the creating of therapy as a formal procedure, people told stories to one another to inform and assist about the world. The term "healing through words" was used over 3,500 years ago in Greek and Egyptian writing. The term psychotherapy was invented in the 19th century, and psychoanalysis was founded by Sigmund Freud under a decade later.

Semantic field
The words care, therapy, treatment, and intervention overlap in a semantic field, and thus they can be synonymous depending on context. Moving rightward through that order, the connotative level of holism decreases and the level of specificity (to concrete instances) increases. Thus, in health care contexts (where its senses are always noncount), the word care tends to imply a broad idea of everything done to protect or improve someone's health (for example, as in the terms preventive care and primary care, which connote ongoing action), although it sometimes implies a narrower idea (for example, in the simplest cases of wound care or postanesthesia care, a few particular steps are sufficient, and the patient's interaction with that provider is soon finished). In contrast, the word intervention tends to be specific and concrete, and thus the word is often countable; for example, one instance of cardiac catheterization is one intervention performed, and coronary care (noncount) can require a series of interventions (count). At the extreme, the piling on of such countable interventions amounts to interventionism, a flawed model of care lacking holistic circumspection—merely treating discrete problems (in billable increments) rather than maintaining health. Therapy and treatment, in the middle of the semantic field, can connote either the holism of care or the discreteness of intervention, with context conveying the intent in each use. Accordingly, they can be used in both noncount and count senses (for example, therapy for chronic kidney disease can involve several dialysis treatments per week).
The words aceology and iamatology are obscure and obsolete synonyms referring to the study of therapies.
The English word therapy comes via Latin therapīa from Greek: θεραπεία and literally means "curing" or "healing".

Types of therapies
Therapy comes in many different forms, and may target mental or physical problems. These types of therapy include cognitive behavioral therapy, dialectical behavior therapy, mindfulness-based cognitive therapy, and physical therapy. Therapists are used daily by many people, and are trained to provide treatment to an individual or group. Therapy was invented in the 1800s by Franz Mesmer, considered the "Father of Western Psychotherapy", who was followed by Sigmund Freud. Therapy is used in many ways to shape and help reform a person. This type of treatment allows individuals to regain gain goals lost or wanting to accomplish. Many individuals come into therapy looking for ways to cope with issues and to receive an emotional release. For example, healing from trauma, in need of support, emotional issues, and many more. Allowing oneself to express your thoughts and feelings go a long way in therapy recovery, this is called the therapeutic process.

By chronology, priority, or intensity
Levels of care
Levels of care classify health care into categories of chronology, priority, or intensity, as follows:

Emergency care handles medical emergencies and is a first point of contact or intake for less serious problems, which can be referred to other levels of care as appropriate.
Intensive care, also called critical care, is care for extremely ill or injured patients. It thus requires high resource intensity, knowledge, and skill, as well as quick decision making.
Ambulatory care is care provided on an outpatient basis. Typically patients can walk into and out of the clinic under their own power (hence "ambulatory"), usually on the same day.
Home care is care at home, including care from providers (such as physicians, nurses, and home health aides) making house calls, care from caregivers such as family members, and patient self-care.
Primary care is meant to be the main kind of care in general, and ideally a medical home that unifies care across referred providers.
Secondary care is care provided by medical specialists and other health professionals who generally do not have first contact with patients, for example, cardiologists, urologists and dermatologists. A patient reaches secondary care as a next step from primary care, typically by provider referral although sometimes by patient self-initiative.
Tertiary care is specialized consultative care, usually for inpatients and on referral from a primary or secondary health professional, in a facility that has personnel and facilities for advanced medical investigation and treatment, such as a tertiary referral hospital.
Follow-up care is additional care during or after convalescence. Aftercare is generally synonymous with follow-up care.
End-of-life care is care near the end of one's life. It often includes the following:
Palliative care is supportive care, most especially (but not necessarily) near the end of life.
Hospice care is palliative care very near the end of life when cure is very unlikely. Its main goal is comfort, both physical and mental.

Lines of therapy
Treatment decisions often follow formal or informal algorithmic guidelines. Treatment options can often be ranked or prioritized into lines of therapy: first-line therapy, second-line therapy, third-line therapy, and so on. First-line therapy (sometimes referred to as induction therapy, primary therapy, or front-line therapy) is the first therapy that will be tried. Its priority over other options is usually either: (1) formally recommended on the basis of clinical trial evidence for its best-available combination of efficacy, safety, and tolerability or (2) chosen based on the clinical experience of the physician. If a first-line therapy either fails to resolve the issue or produces intolerable side effects, additional (second-line) therapies may be substituted or added to the treatment regimen, followed by third-line therapies, and so on.
An example of a context in which the formalization of treatment algorithms and the ranking of lines of therapy is very extensive is chemotherapy regimens. Because of the great difficulty in successfully treating some forms of cancer, one line after another may be tried. In oncology the count of therapy lines may reach 10 or even 20.
Often multiple therapies may be tried simultaneously (combination therapy or polytherapy). Thus combination chemotherapy is also called polychemotherapy, whereas chemotherapy with one agent at a time is called single-agent therapy or monotherapy.
Adjuvant therapy is therapy given in addition to the primary, main, or initial treatment, but simultaneously (as opposed to second-line therapy). Neoadjuvant therapy is therapy that is begun before the main therapy. Thus one can consider surgical excision of a tumor as the first-line therapy for a certain type and stage of cancer even though radiotherapy is used before it; the radiotherapy is neoadjuvant (chronologically first but not primary in the sense of the main event). Premedication is conceptually not far from this, but the words are not interchangeable; cytotoxic drugs to put a tumor "on the ropes" before surgery delivers the "knockout punch"  are called neoadjuvant chemotherapy, not premedication, whereas things like anesthetics or prophylactic antibiotics before dental surgery are called premedication.
Step therapy or stepladder therapy is a specific type of prioritization by lines of therapy. It is controversial in American health care because unlike conventional decision-making about what constitutes first-line, second-line, and third-line therapy, which in the U.S. reflects safety and efficacy first and cost only according to the patient's wishes, step therapy attempts to mix cost containment by someone other than the patient (third-party payers) into the algorithm. Therapy freedom and the negotiation between individual and group rights are involved.

By intent
By therapy composition
Treatments can be classified according to the method of treatment:

By matter
by drugs: pharmacotherapy, chemotherapy (also, medical therapy often means specifically pharmacotherapy)
by medical devices: implantation
cardiac resynchronization therapy
by specific molecules: molecular therapy (although most drugs are specific molecules, molecular medicine refers in particular to medicine relying on molecular biology)
by specific biomolecular targets: targeted therapy
molecular chaperone therapy
by chelation: chelation therapy
by specific chemical elements:
by metals:
by heavy metals:
by gold: chrysotherapy (aurotherapy)
by platinum-containing drugs: platin therapy
by biometals
by lithium: lithium therapy
by potassium: potassium supplementation
by magnesium: magnesium supplementation
by chromium: chromium supplementation; phonemic neurological hypochromium therapy
by copper: copper supplementation
by nonmetals:
by diatomic oxygen: oxygen therapy, hyperbaric oxygen therapy (hyperbaric medicine)
transdermal continuous oxygen therapy
by triatomic oxygen (ozone): ozone therapy
by fluoride: fluoride therapy
by other gases: medical gas therapy
by water:
hydrotherapy
aquatic therapy
rehydration therapy
oral rehydration therapy
water cure (therapy)
by biological materials (biogenic substances, biomolecules, biotic materials, natural products), including their synthetic equivalents: biotherapy
by whole organisms
by viruses: virotherapy
by bacteriophages: phage therapy
by animal interaction: see animal interaction section
by constituents or products of organisms
by plant parts or extracts (but many drugs are derived from plants, even when the term phytotherapy is not used)
scientific type: phytotherapy
traditional (prescientific) type: herbalism
by animal parts: quackery involving shark fins, tiger parts, and so on, often driving threat or endangerment of species
by genes: gene therapy
gene therapy for epilepsy
gene therapy for osteoarthritis
gene therapy for color blindness
gene therapy of the human retina
gene therapy in Parkinson's disease
by epigenetics: epigenetic therapy
by proteins: protein therapy (but many drugs are proteins despite not being called protein therapy)
by enzymes: enzyme replacement therapy
by hormones: hormone therapy
hormonal therapy (oncology)
hormone replacement therapy
estrogen replacement therapy
androgen replacement therapy
hormone replacement therapy (menopause)
transgender hormone therapy
feminizing hormone therapy
masculinizing hormone therapy
antihormone therapy
androgen deprivation therapy
by whole cells: cell therapy (cytotherapy)
by stem cells: stem cell therapy
by immune cells: see immune system products below
by immune system products: immunotherapy, host modulatory therapy
by immune cells:
T-cell vaccination
cell transfer therapy
autologous immune enhancement therapy
TK cell therapy
by humoral immune factors: antibody therapy
by whole serum: serotherapy, including antiserum therapy
by immunoglobulins: immunoglobulin therapy
by monoclonal antibodies: monoclonal antibody therapy
by urine: urine therapy (some scientific forms; many prescientific or pseudoscientific forms)
by food and dietary choices:
medical nutrition therapy
grape therapy (quackery)
by salts (but many drugs are the salts of organic acids, even when drug therapy is not called by names reflecting that)
by salts in the air
by natural dry salt air: "taking the cure" in desert locales (especially common in prescientific medicine; for example, one 19th-century way to treat tuberculosis)
by artificial dry salt air:
low-humidity forms of speleotherapy
negative air ionization therapy
by moist salt air:
by natural moist salt air: seaside cure (especially common in prescientific medicine)
by artificial moist salt air: water vapor forms of speleotherapy
by salts in the water
by mineral water: spa cure ("taking the waters") (especially common in prescientific medicine)
by seawater: seaside cure (especially common in prescientific medicine)
by aroma: aromatherapy
by other materials with mechanism of action unknown
by occlusion with duct tape: duct tape occlusion therapy

By energy
by electric energy as electric current: electrotherapy, electroconvulsive therapy
Transcranial magnetic stimulation
Vagus nerve stimulation
by magnetic energy:
magnet therapy
pulsed electromagnetic field therapy
magnetic resonance therapy
by electromagnetic radiation (EMR):
by light: light therapy (phototherapy)
ultraviolet light therapy
PUVA therapy
photodynamic therapy
photothermal therapy
cytoluminescent therapy
blood irradiation therapy
by darkness: dark therapy
by lasers: laser therapy
low level laser therapy
by gamma rays: radiosurgery
Gamma Knife radiosurgery
stereotactic radiation therapy
cobalt therapy
by radiation generally: radiation therapy (radiotherapy)
intraoperative radiation therapy
by EMR particles:
particle therapy
proton therapy
electron therapy
intraoperative electron radiation therapy
Auger therapy
neutron therapy
fast neutron therapy
neutron capture therapy of cancer
by radioisotopes emitting EMR:
by nuclear medicine
by brachytherapy
quackery type: electromagnetic therapy (alternative medicine)
by mechanical: manual therapy as massotherapy and therapy by exercise as in physical therapy
inversion therapy
by sound:
by ultrasound:
ultrasonic lithotripsy
extracorporeal shockwave therapy
sonodynamic therapy
by music: music therapy
by temperature
by heat: heat therapy (thermotherapy)
by moderately elevated ambient temperatures: hyperthermia therapy
by dry warm surroundings: Waon therapy
by dry or humid warm surroundings: sauna, including infrared sauna, for sweat therapy
by cold:
by extreme cold to specific tissue volumes: cryotherapy
by ice and compression: cold compression therapy
by ambient cold: hypothermia therapy for neonatal encephalopathy
by hot and cold alternation: contrast bath therapy

By procedure and human interaction
Surgery
by counseling, such as psychotherapy (see also: list of psychotherapies)
systemic therapy
by group psychotherapy
by cognitive behavioral therapy
by cognitive therapy
by behaviour therapy
by dialectical behavior therapy
by cognitive emotional behavioral therapy
by cognitive rehabilitation therapy
by family therapy
by education
by psychoeducation
by information therapy
by speech therapy, physical therapy, occupational therapy, vision therapy, massage therapy, chiropractic or acupuncture
by lifestyle modifications, such as avoiding unhealthy food or maintaining a predictable sleep schedule
by coaching

By animal interaction
by pets, assistance animals, or working animals: animal-assisted therapy
by horses: equine therapy, hippotherapy
by dogs: pet therapy with therapy dogs, including grief therapy dogs
by cats: pet therapy with therapy cats
by fish: ichthyotherapy (wading with fish), aquarium therapy (watching fish)
by maggots: maggot therapy
by worms:
by internal worms: helminthic therapy
by leeches: leech therapy
by immersion: animal bath

By meditation
by mindfulness: mindfulness-based cognitive therapy

By reading
by bibliotherapy

By creativity
by expression: expressive therapy
by writing: writing therapy
journal therapy
by play: play therapy
by art: art therapy
sensory art therapy
comic book therapy
by gardening: horticultural therapy
by dance: dance therapy
by drama: drama therapy
by recreation: recreational therapy
by music: music therapy

By sleeping and waking
by deep sleep: deep sleep therapy
by sleep deprivation: wake therapy

See also
Biophilia hypothesis
Classification of Pharmaco-Therapeutic Referrals
Cure
Interventionism (medicine)
Inverse benefit law
List of therapies
Greyhound therapy
Mature minor doctrine
Medicine
Medication
Nutraceutical
Prevention
Psychotherapy
Treatment as prevention
Therapeutic inertia
Therapeutic nihilism, the idea that treatment is useless

References
External links
 Media related to Therapies at Wikimedia Commons
 The dictionary definition of therapy at Wiktionary
"Chapter Nine of the Book of Medicine Dedicated to Mansur, with the Commentary of Sillanus de Nigris" is a Latin book by Rhazes, from 1483, that is known for its ninth chapter, which is about therapeutics
Benefits of Online family therapy