OS X 10.5 included Stacks, a grouping feature that displays files in a 'fan' or 'grid' style in folders on the Dock an updated Finder that incorporates the Cover Flow visual navigation interface first seen in iTunes, iPhone and iPod touch Quick Look, which allows a 'preview' of items by hitting the space bar Spaces, a way to group application windows on more than one virtual desktop Time Machine, an automatic backup utility that allows users to restore deleted files and Boot Camp, Apple's software client to run Microsoft Windows natively on a Mac. Apple introduced OS X Leopard at WWDC 2006, and it became a redefining moment for its software, since it was noted to be the 'largest update of OS X.' It featured a modernized look with a three-dimensional, reflective Dock, a semitransparent menu bar, larger drop shadows for active windows and new high-resolution icons.