Today WordPress has official gone live with the official update to WordPress 3.1. WordPress 3.1 offers countless improvements that will greatly help streamline most of the processes you do daily while maintaining your website. One of which is the admin bar.
The admin bar is a bar, customizable by developers via theme functions, that appears at the top of the page when you are logged in and viewing the site. It offers a number of admin operations to help streamline the workflow of managing a WordPress site.
It is VERY IMPORTANT to note that, similar to the “Edit this Page” links on some pages, this bar will only show up while you are logged in. It is not visible when visitors who do not have user accounts visit the site.
It can also be toggled off, on an individual user account level, via the “Your Profile” section of the admin panel. (Located on Left Side Bar -> Users -> Your Profile. Look for “Show Admin Bar).
In the event that you log in and see the admin bar, don’t panic. It will not alter your actual site’s design, nor will it be visible to visitors who don’t have access to the sites administrator controls.