Pick your favorite Registry key (you do have one don't you?) and describe it's importance in detail.

HKEY_CURRENT_USER would have to be my personal favorite registry key. It is the one that lets me tweak the way my computer looks, acts and is the most fun to change. Actually the other registry keys should pretty much be left alone to avoid serious problems with your computer, unless you really know what you are doing. From HKEY_CURRENT_USER, I can rename desktop system icons, sort favorites menu alphabetically, enable/disable window animations, customize Windows Media Player title bar, it can change the default settings for the way things display of just about everything on my computer. One good thing is it only changes things on my log in, leaving the other user's user's settings alone. This key contains user-specific settings that are built from information in the HKEY_USERS key during the logon process. You should always back up your registry before changing anything to it so if you make a mistake you can restore your old settings.