Files

The foundational asset management feature in Drupal is called File. This feature handles fundamental file management for Drupal’s assets.

Subsystem

File has an entire subsystem in Drupal. Like several other systems, it starts with a File entity. This entity provides all of the standard CRUD operations for files. This entity maintains all of the file storage and the corresponding metadata for a file. Supporting the entity are all of the functions that help derive file size and file extensions, and also perform file uploads during content authoring. At a high level, the file subsystem performs basic asset storage, retrieval, and management capabilities.

Entities leverage files through the use of a file field. Suppose that the content of a particular content type should have an attached file. A file field can be added to the structured content of the content type, which then allows you to upload a file and associate it with the node. Files uploaded to the public...