NOTICE:This tutorial will contain hotkeys like F1,F2,F3,Ect. depending on you computer you may need to hold fn or ctrl at the same time, most likely if you F keys have pictures on them. example:my F2 key has a small sun on it, if i pressed it, it would lower the screen brightness. If i held fn and did it, it would ignore the pictures command.
I dont want to here complaints that it doesnt work. It does!

F1: Hides life,armor,food,hand/crosshair and inventory bar.
F2: Takes screenshot, view my other blog to see how to get to your screenshots.
F3:Shows many confusing things but shows your coordinates and biome
F5: Goes to 3rd person view.
F11: Full screen mode

To turn off these affects press the key again but you'll need to press the F5 one 2 times because it has more than one view.
HAVE FUN!