The core Media module provides a 'base' entity for media assets. This allows you to standardise the way your GovCMS site interacts with media resources. Local files or images, YouTube videos, Tweets, Instagram or Facebook posts, etc. can all be treated in a common way, regardless of where the media resource itself is ultimately stored. Being a standard content entity, you can reference and use this new entity in any place GovCMS knows how to work with them.