A more thorough explanation:

Mercy killing refers to intentionally ending the life of a person who is suffering from a painful, terminal illness. It is also known as "right to die." This term can refer to different types of euthanasia:

• Voluntary euthanasia: This occurs when a person chooses to end their life to avoid further suffering. It can be passive (when a person refuses or withdraws consent for lifesaving medical intervention) or active (when a person is given medication to end their life).
• Non-voluntary euthanasia: This occurs when a person is unable to consent to life-ending measures.
• Involuntary euthanasia: This occurs when a person does not want or resists life-ending measures.

Active voluntary euthanasia is legal in some countries, such as Belgium, Canada, Colombia, Luxembourg, the Netherlands, Switzerland, and some states in Australia. In the United States, some states have recognized a right to active voluntary euthanasia through death with dignity statutes. However, non-voluntary and involuntary euthanasia are illegal in all countries.

For example, if a person with a terminal illness is in severe pain and chooses to end their life with medication, this would be considered voluntary euthanasia. If a person is in a coma and unable to make decisions, and their family decides to end their life to avoid further suffering, this would be considered non-voluntary euthanasia. If a person is against ending their life but is given medication to do so anyway, this would be considered involuntary euthanasia.