Toggling development mode

A gear icon (orange in TYPO3 6.2, monochrome since TYPO3 7.x) in the toolbar lets you manage your domains / zones:

Development mode is a way for you to make changes to your site, and see the changes immediately. By entering development mode, you will bypass CloudFlare’s proxy and suppress minification. As a result, as you make changes to images, CSS or Javascript, the changes will appear immediately. Development mode stays on for three (3) hours and then automatically toggles off.

In TYPO3 7.x, the gear icon shows a badge with the number of zones in development mode (if greater than 0).