Oracle Database Discussions

I been trying to get a firm definition as to what is a bind variable and a global variable and what are the differences.

Reading the Oracle PL/SQL text i see that a bind variable can also be known as a host variable.

Also a bind variable is an "enviroment" variable but not a "global" variable (as per the book)

Im a bit confused as to what exactly is an "enviroment" vs "global" variable.

Isnt a bind variable, technically also a global variable? As when i declare a bind variable it can be used for any other procedures/functions/SQL while my session is still active.

Little confused about the distinction.