The Inbox is for new created stories etc. which are not initially placed in the Storymap
A user can have different roles and thereby have acces to view, edit or perform different tasks.
Users are invited by email. The user invite specifies the roles and/or team memberships of the user.
A Preplanned list is an ordered list of product backlog items that are yet to be explicitly planned. Preplanning stories/epics is to obtain an early grouping of items for a future release.
A team is a collection of users. A team can be mentioned in comments and assigned to tasks.
A site is an organization account.
The milestone specifies a deadline. Themes, epics and stories can be linked to this milestone to indicate that they must meet the deadline.
A Sprint is a time-box during which a “Done”, useable, and potentially releasable product increment is created.
A release is a special type of milestone. It is the base for the planning in the Product Backlog.