Immortality (or eternal life) is the concept of living in a physical or spiritual form for an infinite length of time.
As immortality is the negation of mortalitynot dying or not being subject to deathit has been a subject of fascination to humanity since at least the beginning of known history. The Epic of Gilgamesh, one of the first literary works, dating back at least to the 22nd century BC, is primarily a quest of a hero seeking to become immortal. What form an unending human life would take (as well as whether it is subject to incapacitation), or whether the soul exists and possesses immortality, has been a major point of focus of religion, as well as the subject of speculation, fantasy, and debate.
It is not known whether human physical immortality is an achievable condition. Biological forms have inherent limitations which may or may not be able to be overcome through medical interventions or engineering. As of 2009, natural selection has developed potential biological immortality in at least one species, the jellyfish Turritopsis nutricula.
I believe that we will in the near future be able to sufficiently extend what natural lifespan humans have now to allow for further application of technological and scientific advances - in essence making us immortal as our lifespans are continuously extended as science advances. This idea has been espoused by many life-extension proponents and transhumanists such as DeGray and kurzweil who believe that this technology will arrive before they die.
Regardless of how you want to extend life the goal is essentially to be able to live on indefinitely, with death becoming a choice rather than a consequence of your physical structure.
Think about that for a second, life eternal until you pull the plug.
And if you don't end your life and plan on living on forever then you're in for a whole bunch of potential problems. First of all, you'll have to deal with the end of the universe itself.
Which is the least of your concerns.
You'll also have to somehow help create or hope for there being some sort of civilization continuing it's existence alongside you, or modify yourself so that your psychology doesn't require outside input from a greater society (but that might leave you a rather empty husk with no more awareness than a plant), or community of other immortals to aid you in this task.
But just interacting with other beings pose a danger to your existence, there is always the possibility of someone at some point in time not approving of your continued existence - and if you plan on living forever then such a being or group of beings will inevitable pop up.
The very technology required to keep you alive might lead to your eventual downfall, by the time we can avoid universal death and keep a mind functioning for aeons you better have access to a great deal of power to protect yourself from dangerous use of the future technology and science. And if our world and past is anything to judge from then it seems that attacks always precede defense (we can barely protect ourselves from nukes and it's been how long?)
Immortality seems like a really big hassle, and in the process of becoming and being an immortal you might nave changed so much that you can no longer be considered you in any meaningful sense. Sure, that's the case today but in our relatively short lifespan it's not that big of a problem. While I'm a different person when compared to me as a child I still posses a great number of traits from then that let me at least rationalize that I'm the same person. But over the course of millions and billions of years I'll probably have completely changed all my traits a million times over or more.
So with all that in your mind I have a couple of questions for you:
Would you like to be immortal?
And if so, how long do you think you'd like to live?