What is group policy in active directory ? What are Group Policy objects (GPOs)?

Group Policy objects, other than the local Group Policy object, are virtual objects. The policy setting information of a GPO is actually stored in two locations: the Group Policy container and the Group Policy template.

The Group Policy container is an Active Directory container that stores GPO properties, including information on version, GPO status, and a list of components that have settings in the GPO.

The Group Policy template is a folder structure within the file system that stores Administrative Template-based policies, security settings, script files, and information regarding applications that are available for Group Policy Software Installation.
The Group Policy template is located in the system volume folder (Sysvol) in the \Policies subfolder for its domain.