The eXMiller component is a file-folder-view component that uses miller columns visualization to display system folders and files. The Miller columns (also known as Cascading Lists) are a browsing/visualization technique that can be applied to tree structures. The columns allow multiple levels of the hierarchy to be open at once, and provide a visual representation of the current location. It is closely related to techniques used earlier in the Smalltalk browser, but was independently invented by Mark S. Miller in 1980 at Yale University. Miller columns are most well known today as the "Columns view" mode of the Mac OS X Finder, as well as the "Browser" view in iTunes.