Five years ago I was introduced to Google Docs. Just recently I was re-introduced to it and I was impressed at the upgrades made since. It is offered by Google which is found within Google Drive. Google Docs offers: Document, Presentation, Spreadsheet, Forms and Drawing.
Google Docs allows users to create documents online while collaborating in real-time with multiple users. Each person you give permission to can edit or view document. There is a chat box that would allow you to communicate with other collaborators. A history of work is saved. You can have access anywhere and store files safely. Just sign in with a gmail account to Google Drive and begin.
Thanks Mario for reminding me of Google docs.