Inverts page content from black text on white to white text on black. Handy for reading late at night under low light conditions.
Takes your normal black-text-on-white pages and inverts them to white-text-on-black. It's great for preventing your significant other from waking up while working in bed.
Simple enough, just hit the icon and it inverts the page you're on. Subsequent page loads on any tab will also be affected by it.
After you turn it off, just refresh the page you're on to take things back to normal. Once off, it will no longer affect anything.