This area shows the actual game, that is your character, other characters, the landscape, etc.
The slots shown here indicate your equipment. This includes your weapons, your armor and everything else you wear.
In this window you will see what other characters (players and NPC's) say to you, and you will be able to follow the
This list shows your stats, that is your attributes, your skills and spells. If you're in shop-mode, it will show the
contents of the shop instead. Same goes for loot-mode.
This is your backpack. It contains all the items you're carrying with you, but which you are not using at the moment.