Google Docs is a platform where you can create a document and upload it on Google server. From that you can share the document with different users to work on same time on that.
Yes, it is real time.
For small offices, where administrator doesn’t want to manage a server on its own, they can go for Google Docs. Brief features of Google doc are:
1) Create a document in many formats like DOC, XLS, ODT, ODF, RDT, PPT etc
2) Upload the document on a secured server
3) Share the work with other people by inviting them
4) Publish the work document from the server as web page
Those who are using Google doc for the official purpose are really making so much of money by running their small business of collaborative development without any cost.