Soul Bound

Soul Bound is a binding mechanic to designate an item which cannot be placed on the Auction, mailed, or placed in the inventory of another character. Some items are always Soul Bound. Soul Bound is not to be confused with Account Bound. Soul Bound is per character, items such as Item Recovery Offering are Soul Bound, but also Account Bound. Thorn Gear is Account Bound.

The difference with Soul and Account bound is Soul Bound items are lost (or used) upon death, cannot be saved for use with another character or traded/gifted to other players. Account Bound items don't have the same limitations in that they can be shared within your account or used on another character. Also they will be sent to your Mailbox upon death. Soul Bound items not consumed upon death are lost. Such as extra Item Recovery Offering's.

Thorn Gear is an example of Account Bound gear that isn't lost upon death.