If you're like me and got an IMAC 27 in 2009-2011 then you know the computer screens have had some big issues. One of them is clouding where you get dark shading. Most people have called Apple which is a pain even if you're still under warranty. If you don't have warranty then Apple will charge you 800-1000 for a new screen to be put it. It's a rip off and FINALLY you can do it on your own. I did my best to make it easy. It's about a 1/2 hour fix. Good Luck Billy