Everything You Wanted To Know About Sharing In Google Docs
"One of the most powerful aspects of Google Docs is the ability to share
documents, spreadsheets, and presentations with other individuals and
collaboratively edit those documents together in real-time from anywhere
in the world. Collaborators on a document can view, comment on, or even
made changes to the document, depending on the permissions you give
them. There's never a reason to email document attachments or merge
edits from multiple copies of a document again."