this pretty much does what you'd expect it to - darken all the backgrounds and certain other elements of webpages (that allow it to) :D it works really well for most websites for me! sometimes i have to turn it off on already darkened websites since it may make it harder to see the text and such, but i wouldn't expect this to be perfect. i love it simply for what it does for the majority of websites i visit! highly recommend checking this one out!