Preview Page

Simply click on the icon in the Your Pages list.  The preview page will open in a new window.

WHAT? Most of your pages can be previewed without having to publish. 

WHY? This gives you the ability to review your content and make sure you've said what you want to in the way you want to say it.  Clicking the Preview button normally opens the preview page in a new window so you can quickly go back to your editor and edit the page for any mistakes. 

WHEN? Preview before you Publish should be your rule of thumb.