Various functions on Derpibooru have keyboard shortcuts to make browsing easier and faster.
|F||Favourite image (image under the mouse pointer)|
|U||Upvote image (image under the mouse pointer)|
|J||Previous image (in global index terms, the image posted after the one you're looking at)|
|K||Next image (image posted before current one)|
|S||Open source URL|
|L||Open tags for editing|
|I||Go to index page containing the image being displayed|