Global variable

A global variable is a variable which is valid throughout the lifetime of the program's execution.

By definition, it does not have a scope.

Example of a global variable in C

#include <stdio.h>
int number = 6;

void printNumber() { // no parameters...
    printf("%d", number); // ... but we can still access 'number'
}

int main() {
    number = 12; // assign a new value to global variable 'number'
    printNumber(); // prints '12'
}

Comparison to local variables

Local variables are only valid inside a specific scope.

Usually, this scope is a code block, such as an if statement or subroutine (function or procedure).

Global variables on the other hand are not bound to a specific scope or code block, but can instead be accessed anywhere in the program.