There are 6 types of storage in Revelation Online: inventory, storage, temporary, apparel, resources, and purchases. However, not all of these are unlocked at the beginning.
 

Backpack Expanders

All the above-mentioned storages can be expanded by using backpack expanders. If that sounds good to you, they can be obtained from the Aurum Shop or by collecting login rewards.

Inventory Bags

There are many different ways to acquire inventory bags: you can purchase them from NPCs, claim login rewards, or get them from the Aurum Shop.
 
The best inventory bag in the game is an Ornate Cotton Pack which provides 24 inventory slots each. Once you’ve unlocked extra bag slots you can equip your extra bags – simply drag them into an available bag slot.

Temporary Tab

As the name suggests, this is temporary storage. Most of the loot you acquire from chests or NPC exchanges will first appear in this temporary inventory, especially if your main inventory is currently full. You can access this storage at any time by pressing B and selecting “Temporary”.
 
NOTE: Temporary inventory is wiped whenever you log out.
 

Apparel Tab

Only cosmetics and costumes can be stored in this inventory. You can access apparel storage much like the rest – by pressing B and selecting “Apparel”.

Purchases Tab

Any and all purchases from the Aurum shop go directly into the Purchases inventory.

Storage Tab

Storage can be used to store items of choice, as well as your Imperial Coins. To access the storage, you will need to talk to an Inventory Attendant, many of which are conveniently scattered throughout various cities in Nuanor.

Resources Tab

This space is used to hold all your crafting materials. It is unlocked by reaching Chapter Three of the crafting life tree and obtaining a particular scroll. Once you have unlocked this scroll, you can turn it into an Inventory Attendant and receive a purple quest to unlock the resources inventory.