"Turn off the Lights", also referred to as ToTL, is an extension for Google Chrome, which you can find in the Chrome Web Store. Basically what this extension does, is "turns off the lights" to focus your viewing on the main point. One place where this is genius, is on YouTube. when you turn on the extension, the video will stay at the same brightness, but the related videos, comments, description, etc. will become much darker. Go ahead and try it for yourself, it's a great extension, and is something I will be using a lot.