system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does exposure to radiation kill my body? What exactly does it do to me?

I think it is about time I understand how radiation kills a human being and why is it bad after all the Hollywood films I've watched over the years and the research into Chernobyl I've done. Why is it so deadly?
gpt
Radiation is bits and pieces of atoms that fly around at high velocity.  When they hit the molecules in your body, they can destroy them by knocking atoms out of alignment.  Most molecules can easily be repaired or replaced.  DNA can also be repaired, for the most part.  But if too much damage is done to DNA in too short of a time, your body can't keep up with the repairs.  When this happens, the DNA accumulates errors, which can eventually lead to cell death or cancer.