Euthanasia is the practice of ending the life of a patient to limit the patient’s suffering. The patient in question would typically be terminally ill or experiencing great pain and suffering. The word euthanasia itself comes from the Greek words eu (good) and thanatos (death). The idea is that instead of condemning someone to a slow, painful, or undignified death, euthanasia would allow the patient to experience a relatively (good death).

Different practices fall under the label euthanasia. Here are some distinctions demarcating different versions:
- Active euthanasia: killing a patient by active means, for example, injecting a patient with a lethal dose of a drug. Sometimes called aggressive euthanasia.

- Passive euthanasia: intentionally letting a patient die by withholding artificial life support such as a ventilator or feeding tube. Some ethicists distinguish between withholding life support and withdrawing life support (the patient is on life support but then removed from it).

- Voluntary euthanasia: with the consent of the patient.
- Involuntary euthanasia: without the consent of the patient, for example, if the patient is unconscious and his or her wishes are unknown.. Some ethicists distinguish between involuntary (against the patient’s wishes) and nonvoluntary (without the patient’s consent but wishes are unknown) forms.

- Self-administered euthanasia: the patient administers the means of death.
- Other-administered euthanasia: a person other than the patient administers the means of death.
- Assisted: the patient administers the means of death but with the assistance of another person, such as a physician.

There are many possible combinations of the above types, and many types of euthanasia are morally controversial. Some types of euthanasia, such as assisted voluntary forms, are legal in some countries.
- Mercy-killing: The term (mercy-killing) usually refers to active, involuntary or nonvoluntary, other-administered euthanasia. In other words, someone kills a patient without their explicit consent to end the patient’s suffering. Some ethicists think that.

- Physician-assisted suicide: The phrase (physician-assisted suicide) refers to active, voluntary, assisted euthanasia where a physician assists the patient. A physician provides the patient with a means, such as sufficient medication, for the patient to kill him or herself.

Some instances of euthanasia are relatively uncontroversial. Killing a patient against their will (involuntary, aggressive/active, other-administered), for instance, is almost universally condemned. During the late 1930’s and early 1940’s, in Germany, Adolf Hitler carried out a program to exterminate children with disabilities (with or without their parent’s permission) under the guise of improving the Aryan race and reducing costs to society. Everyone now thinks this kind of euthanasia in the service of a eugenics program was clearly morally wrong.