GM: Global variables
From GMpedia.org Wiki
A global variable in Game Maker is a variable that doesn't concern any particular object at all. Built-in global variables concern the room settings, such as speed, views, backgrounds, etc.
[edit] Regular Global Variables (Not built in)
If an object that is called o_happy has this piece of code:
{
global.happy=6;
}
Then any other object could access the same variable "global.happy" and edit it. No object is concerned with it so if o_sad wants to change global.happy to 8 the following piece of code is used:
{
global.happy=8;
}
Different objects cannot have different global variable values with the same names as global variables concern no object.

