Attachments are files that are attached to AODocs documents. Attachments are stored in Google Drive and are owned by the storage account of your library.
Attachments are listed in the sidebar of your document. In Document Management libraries you can also access attachments in the Properties panel, under Attachments.
Documents in Team Folders and Secured folders have exactly one attachment.
A single attachment in a Secured Folder
Documents in Document Management libraries can have no attachments, one or several attachments.
Multiple attachments in a Document Management library
Other actions for managing attachments are specific to Document Management libraries. These include adding new attachments, attaching files by drag and drop, and removing attachments.