I can see a "Development Mode" flag for the User-Records under System Administrator profile and not able to see in other Profiles.
I am using the DEV ORG. Can someone tell me the significance of this Flag and its impact on the system based if its selected or not selected?
With development mode enabled, you will be able to edit visualforce page and classes right in the browser, without using developer console. Below every Visualforce page, you get a new section (which can be minimized) to edit it as shown below.
You can also see the "view state" of the visualforce page.