Open All Files in a Folder: Command+O

This shortcut is particularly useful when you have a folderful of screenshots or downloaded images that are nor clearly named. To flick through them, open the folder, type Command+A to select all, then type Command+O to open all. Preview will open all images in one window. Click on a thumbnail to see the image you want, or click on arrows to go through the images one by one.

Command+A

Command+O