Cryonics is the preservation of the brain by cooling to subzero temperatures.
The goal of cryonics is to preserve the information in the human mind. This includes the memories, personality, emotions, and aspirations of the person, everything that makes them a unique individual. If we preserve the physical network of neurons with high enough quality, then the person isn't really dead yet. They could be revived with high enough technology
Repair and Revival
We can't yet repair or revive anyone yet, not even close. It will probably be well over 100 years before we can revive anyone, but that does not invalidate the practice of cryonics. Repair will require very advanced technology but no new physics. In other words, it's nothing more than a complex engineering problem. As with other complex engineering problems, it's most likely simply a matter of time before we solve it.
There are no alternatives to brain preservation. If a brain is destroyed, the mind is always destroyed with it, no matter how much we might wish otherwise. Cryonics is the only strategy that has been shown to have even the remotest chance of preserving the mind. The choice is either brain preservation or permanent death.
Cryonics is about living. It's about being there for your grandchildren who might never have to endure cryonics themselves. Cryonics is about love of family and the refusal to let happy memories die.
Quality preservation doesn't come easily. Most cases are severly compromised by obstructive laws, vast distances, poor planning, and tight budgets. We need cryonics facilities in every major city just as a basic starting point. Consumers of cryonics services cannot be passive. There's a lot that each person can do to help cryonics grow and to improve their own treatment.
This scan demonstrates the complexity of neurons.
Memories are encoded in these structures.
There are 100,000,000,000 neurons,
each with about 2000 synapses (connections)