Human transmutation:
There's two taboos/crimes in alchemy.
Your not allowed to make gold OR transmute human souls.
Human transmutation is basically bringing someone back from the dead
Nobody has succeeded
Philosophers Stone:
A red stone created from multiple human lives and basically can do litterally anything
Homunculus:
An artificial human created when someone preforms human transmutation
In brotherhood this father guy creates them
Automail:
It's kind of like a prosthetic leg or arm or yk something like that
But it's made from metal or steel and works a lot better and is stronger
