Clarity on global variables

[JonWayn]

I have some code in which I have global variables which are accessed within functions but only in some cases they are recognized. I read online that this can be overcome by adding the line global <var> at the top of the functions that access the variable, but why is it that other variables declared globally are recognized by the same function? Does the type of the variable matter - in the case I am dealing with the variable that is not recognized is an integer while the recognized ones are strings.

Thanks for any help