See Thumbnail Badges and Ratings?

Go to a collection in Grid view and two-finger tap (tap the screen one time using two fingers) and image info appears on your thumbnails. Each time you tap, a different set of info appears, from thumbnail badges (shown above; tiny icons that show you whether an image has been edited, or has a star rating, or flag), to the camera data (f-stop, shutter speed, etc.), to the filename. Each time you tap, it toggles through another set until it hits Hiding Info, where it just shows the images without any badges or text.