Immortality is the concept of eternal life. Some modern species may possess biological immortality.

Some scientists, futurists, and philosophers have theorized about the immortality of the human body, with some suggesting that human immortality may be achievable in the first few decades of the 21st century with the help of certain technologies such as mind uploading (digital immortality). Other advocates believe that life extension is a more achievable goal in the short term, with immortality awaiting further research breakthroughs. The absence of aging would provide humans with biological immortality, but not invulnerability to death by disease or injury. Whether the process of internal immortality is delivered within the upcoming years depends chiefly on research (and in neuron research in the case of internal immortality through an immortalized cell line) in the former view and perhaps is an awaited goal in the latter case.

What form an unending human life would take, or whether an immaterial soul exists and possesses immortality, has been a major point of focus of religion, as well as the subject of speculation and debate. In religious contexts, immortality is often stated to be one of the promises of divinities to human beings who perform virtue or follow divine law.