Euthanasia (from the Greek word eu, “good”, thanatos, “death”) is the practice of terminating the life of a person or an animal because they are perceived as living an intolerable life existence. This may be achieved in a painless or minimally painful way either by lethal injection, drug overdose or by withdrawal of life support. Euthanasia of humans is a controversial issue due to conflicting religious and humanistic views. Terminology and laws shift over time, geographically and globally, causing a great deal of confusion.

A more broad definition of euthanasia may be active or passive. It can be voluntary, non voluntary or involuntary. (Kark Binding and Alfred Hoche one of the pioneer users of the 3 types of Euthanasia). Physician assisted dying is where doctors provide a prescription for the terminally ill patient to hasten their death. The patient chooses the time and circumstances of his/her own death. Voluntary euthanasia, occurs when a competent adult, patient or their surrogate gives full consent and a request or instructions either directly or indirectly to not resuscitate. Patients have the right to refuse treatments. It could be defined as a happy death. (Thomas Youk with ALS was assisted by Dr. Jack Kevorkian).

Nonvoluntary euthanasia is without a fully informed consent or informed request by a competent adult patient or that of their surrogate. An example might be if patient has decisional capacity but it is not told they will be euthanized or a patient is not conscious or lacks decisional capacity and the surrogate is not told the patient will be euthanized.

Involuntary euthanasia, occurs over the objection of the patient or surrogate. An example of these might be if a patient with decisional capacity or their surrogate is told what will happened. The patient or their surrogate refuses or patient is euthanized anyway. This is generally considered murder.

Terminal sedation is a combination of medically inducing a deep sleep and stopping other treatment, with exception of medication for symptom control (such as analgesia). It is considered by some, but under current law and medical practice it is considered a form of palliative care.

Mercy Killing is a term used of some cases of euthanasia. Typically it refers to termination by a someone other than a doctor, such as a parent, who perceives the individual to be suffering. The patient may give or cannot consent. Patient is not asked or refuses.