Work in progress for the update of the 12 Feb 2018 (modification on the UI)
You can access your inventory by pressing "I" key (or F3), by default. The inventory is split up into four parts; Character Info, Armor slots, tool/weapon slots, and inventory slots both internal and backpack.
The character info is divided into lines.
1. Character name
2. Clans Name (click on the X to cancel)
3. Reputation (Renegade/Punisher) (click on the X to become neutral when possible)
4. Armor Effectiveness percent
5. Character Speed percent (depending on armor weight)
6. Tool/weapon effectiveness percent.
About the armor piercing percentage on some weapons: "If you hit a player who have 50% armor value with weapon (without Armor Piercing) which cause 100 dmg - you will deal 50 dmg. In the same case but with 20% Armor Piercing you will reduce his armor by 20% so you will deal 60 dmg"
7. Tool/weapon Speed (in seconds)
The slots are divided by the tabs on the left hand side. By default the key to switch between the slots is "Q". This key can be used in and out of the inventory. The easiest way to put a tool into the slot is to "SHIFT + Left Mouse Click". This will insure the item goes to the right slot. The left hand slot is the main tool. The right hand slot is the aux item to the main item. For example, you can have a bow in the left slot and arrows in the right slot, or an axe in the left slot and a torch in the right.
There are 26 slots of inventory starting out. You can get more by crafting a Linen Backpack. Tools require two slots high.