Images can be sorted into 3 categories (Yes/Maybe/No) for easy navigation.
You can move a single image (click to select) or multiple images (CTL or Shift + click). With the image(s) selected hit the corresponding sort icon (Star Icons at the bottom of the screen) or use the keyboard shortcut.
Yes = Full Star (Green) / 1 on Keyboard
Maybe = 1/2 Star (Yellow) / 2 on Keyboard
No = Empty Star (Red) / 3 on Keyboard
You can navigate folders by clicking the corresponding tab at the top of the thumbnail panel. The (number) next to the folder title shows the number of images in that folder.