Shared Storage is a new storage system designed to enable sharing between all characters on a given account!.Until now, your only options to share items between characters were to mail them individually, deposit them into a personal chest at your home, or have a friend hold them while you switched characters.
Shared Storage can be accessed by visiting any Vault-keeper and opening the standard Vault interface you are already familiar with. A new button, “Open Shared Storage”, will be available on the Vault interface:

Any items currently in your standard Vault can be easily transferred to Shared Storage and vice-versa, simplifying the process of sharing items with your other characters.
Shared Storage Interface
The Shared Storage interface has new features to help you manage your shared items. You can sort items alphabetically by name (A-Z, Z-A) and filter by item type. The list is populated dynamically from the items in your shared storage space.

Filtering items is as easy as selecting the Filter drop-down menu and picking the item-type to display:

For your convenience, bound items can be stored in Shared Storage -- but only the character they belong to can retrieve them. The Filter Bound Items option will hide items that don’t belong to your current character. Unique items cannot be stored in the Shared Storage.
This new feature should make managing items across multiple characters much easier!