For questions about the web version of Google Documents, the word processor from Google. For questions about the file manager application use tag [google-drive] instead. Do NOT normally apply both to the same question.
Google Documents is part of Google Drive and allows the user to create new documents on the web interface (as opposed to using a local word processor software). Documents on Google Drive can be shared with others to collaborate, or simply used as a document editor.
Do's
The tag can be used on itself or in combination with other tags:
google-documentsgoogle-apps-script or
google-documentsgoogle-drive*pdf
(* to indicate that you want to convert the document to PDF in Google Drive)
Don'ts
Do not use the google-drive tag in combination with the google-documents tag, to point to the Google Documents. This will make both tags contaminated.