Some say that a person dies when buried in his grave, Others say that a person dies when people utter their name for the last time. Or in other words when he is Forgotten
Some believe that a person dies when he stops feeling some who consider it a more real belief that a person dies when his heart stops beating, this seems the most logical option, doesn't it? "Humans Die's When The Heart Stops Beating" Right?
Technically, you probably know the following, there are cases when the heart stops, but it can be restored after attempts by dumbfounded doctors who inject with chemicals that help restore the pulse.
On the other side, some cases are in a coma for long periods. Their heart remains in a state of pulse, but the body remains still. Can this be considered a Death?
Let's take another example, law considers a person who has been missing for a long time to Be Dead.
If we take into account the technological development and assume that we were able to keep your body intact after your heart stopped beating. Do we call you a dead or in a coma?
As you see, dear reader, the definition of death varies from one perspective to another, The definition of death has never been an easy thing throughout history
lets start from the beginning, shale we?
in 1846 a French doctor named Eugène Bouchut figured that "if a person’s heart had stopped beating, they were surely dead"
He suggested using the newly invented stethoscope to listen for a heartbeat – if the doctor didn’t hear anything for two minutes, they could be safely buried 
The invention of the EEG – which can be used to identify brain activity – dealt the final blow. Starting in the 1950s, doctors across the globe began discovering that some of their patients, who they had previously considered only comatose, in fact had no brain activity at all. In France the mysterious phenomenon was termed coma dépasse, meaning literally “a state beyond coma”. They had discovered the ‘beating-heart cadavers’, people whose bodies were alive though their brains were dead." 
Restore the heartbeat after it stops. Not only did that mean a return to life, but also mean that we should review the human beings' definition of life.
Especially that technological advances contributed to the invention of machines such as Feeding tube, artificial respirators, catheter and mechanical ventilation, machines that help to continue living despite the failure of your organs,
These devices made the definition of death by stopping your vital organs, such as breathing, apparently unreasonable, especially as they increase the possibility of your ability to help those functions. Especially because there are sources that say that the heart and lungs may stop not because of a problem in the them, but in the brain itself in place inside your brain called brain stem.
"Physicians, health care workers, members of the clergy, and laypeople throughout the world have accepted fully that a person is dead when his or her brain is dead. Although the widespread use of mechanical ventilators and other advanced critical care services have transformed the course of terminal neurologic disorders. Vital functions can now be maintained artificially for a long period of time after the brain has ceased to function. There is a need to diagnose brain death with utmost accuracy and urgency because of an increased awareness amongst the masses for an early diagnosis of brain death and the requirements of organ retrieval for transplantation [...] Process for brain death certification has been discussed under the following:[...] 2- Exclusion of any condition that might confound the subsequent examination of cortical or brain stem function.." Ajay Kumar Goila and Mridula Pawar 
Thanks to these devices, we can avoid declaring the status of fulfillment, and instead we compensate the jobs with these machines.
So does all this mean that humans can exchange all their bodies with some prostheses and some machines? and if this happens where will our consciousness go? The consciousness is difficult to understand and the reason is that it cannot be clearly explained
From the above, we can say that the word death has no consistent definition throughout history and with scientific development this definition renews to break.
Death and life has always been a mystery.