Globals are the underlying storage structure for InterSystems IRIS® Data Platform. One of the hallmarks of InterSystems IRIS is its ability to store data once and allow you to access it using multiple paradigms. While it is not necessary to work directly with globals, it can be very useful to understand how InterSystems IRIS uses them and to see the advantages they provide.
Introduction to Globals
First Look: Globals
Read all about it
Introduction to Persistent Objects — Globals
Multidimensional data access