In early versions of Windows and Internet Explorer, the Explorer bar was a panel on the side of the window that gave quick access to different browsing tools. It was organised into 5 distinct categories, namely Search, Favorites, Media, History, and Folders.
Each of these categories switched the side panel to show a different kind of content, for example the Favorites category listed bookmarked pages, while the History category listed recently visited pages, and the Folders category showed the file system structure. Splitting the bar into these five separate categories let users quickly jump between different browsing and file tasks from one panel.
The other numbers listed do not match the number of categories the Explorer bar was actually divided into in this interface.
Exam tip: remember the Explorer bar's five categories as Search, Favorites, Media, History, and Folders, a useful memory aid is to think of them as the five common ways users navigate a browser or file window.