Function Keys Edit

Pressing: F1
Result: Opens and Closes the help guide/window, which can also be opened in your browser in a PDF format
Result: Removes All of The icons on your screen, enabling you to take great screenshots
Result: Will bring up/show you your in game time, Position:X, Position:Y, Position:Z or location on the map/world, memory usage, Graph: Frame Time, Send/Receive Bytes
Result: Shader Features i.e Height. Normal's, Dump Type
Result: Takes a screenshot of your game play, which becomes available in your steam content que after you exit the game, enabling you to either delete or upload the screenshot