The charms bar is the new universal menu in Windows 8 to access commonly used settings
To access this menu move your mouse pointer to the top or bottom right corner (or swipe in from the right of the screen if using a tablet), and you will see the five icons appear

As you move the mouse up/down to select one of these icons the screen will change as below, showing the date/time, network status, battery level and the five available options

These options are explained in more detail below:-

Date/Time, Network and Battery Status: This area shows the current date/time as well as icons showing the current network/internet connection status and battery level

Search: Opens up a search pane which allows you to search local files, settings, applications and the web

Share: Allows you to share the currently selected item via email, post it to you social network, or to add it to your reading list to view later
Start: Opens up the start screen

Devices: Options to allow you to Project (send current screen to an external device such as a projector or second display), Print or Play (stream video/music to an external device)

Settings: Opens up the settings screen which shows settings for the currently active program, as well as shortcuts to change PC settings, notifications, screen brightness, power settings and volume