A user can attach either physical files (e.g. documents such as PDFs, Word files, Excel sheets, etc.) to any business object (i.e. accounts, opportunities, quotes, etc.) or URLs pointing to either files or folders on collaboration platforms (such as SharePoint, Dropbox, SAP Jam, etc.). For this, the administrator can define a so called 'Attachment Usage' which describes the type of an attachment. This can be done under 'Administration' -> 'Master Data Management' -> 'Attachment Usage'.
The attachment usage can then be selected when uploading / storing attachments such as files and / or links on the business object:
On an attachment usage, the administrator can further define the visibility of the respective usage by restricting the visibility:
In the above figure, the administrator restricts the usage 'Product Image' not to be used for links / URLs, but only for attachments (i.e. files).