Shiva --
The Global.mpt file is the template file saved on your PC's hard drive when
you install Microsoft Project. This template file contains all of the
default objects that ship with Microsoft Project, including Views, Tables,
Filters, Groups, Macros, Toolbars, Calendars, etc. A good way to think
about the Global.mpt file is to describe it as your "library" of default
objects.
When you launch Microsoft Project, the software opens the Global.mpt file in
the background, which gives you all of these default objects. If you create
your own personal custom Views, Tables, Filters, Groups, etc., you can copy
them to the Global.mpt file (using Tools - Organizer), which makes them
available in all current and future projects. Hope this helps.