A Global ID is an app wide URI of the form gid://YourApp/Some::Model/id that uniquely identifies a model instance.

This is helpful when you need a single identifier to reference different classes of objects, for example in job scheduling, when one needs to reference a model object rather than serialize the object itself. Another example is a drop-down list of options, consisting of both Users and Groups. One has then a universal identifier that works for objects of both classes.

This package is part of the dependencies for the Ruby on Rails framework.