What is global in DRL file?

The term global is used in drools to declare a global variable. The global variable is the one that all of the rules in a DRL file will see.
Because changes in a global variable are not signaled to the working memory, global variables must be utilized with caution in a DRL file. If, for example, you use a list variable as a global and add a value to a list in any rule, and one of those rules checks if list size() > 0, the rule may not trigger in this instance. Any type of object can utilize a global variable.