The board is the main part of the Agile Support module in YouTrack, which allows you to visualize your daily activities. On the board you can view the status of all your work items, group your tasks in user stories by creating swimlanes and estimate and move your tasks around the board.
The board shows tasks in the columns that represent the current state of the task (issue). You can configure board's parameters in the Board settings section.
Columns on the board correspond to issue States. A column is shown on the board if the corresponding state is selected in Settings.
You can configure Board columns in the settings pane of the same name.
By default, the four column are displayed: Open, In Progress, Fixed, and Verified. To enable/disable showing a column, select/deselect checkbox for the corresponding state.
A sprint is a set period of time, during which specific work has to be completed and made ready for review. In YouTrack terms, a sprint corresponds to a version number. When you create a sprint, the same value is added to the Versions bundle of your project. Likewise, if you add a new version to the Versions bundle, a new sprint will appear in the list of sprints for your project.
The backlog is a collection of not yet estimated features and tasks that await planning and implementation. In other words, it's the list of work your development team should address during the project release cycle.
In terms of YouTrack, a backlog is a saved search. By default, for each project the following saved search is created automatically and is used as the backlog:
That is, by default the backlog of a project contains all unresolved issues in the project with empty "Fix versions" field.
For more details please refer to the Working with Backlog page.
Generally, a swimlane contains a feature with all its subtasks. In terms of YouTrack, a swimlane is an issue of specific type (by default, Feature) and all issues that are linked to it as 'subtask'. The issue field and its value that define a swimlane can be customized in the Board's Settings.
See Configuring the Board page for details.
Task card (or just a card) represents an issue of any type except the issue type that is selected to identify swimlane.
Orphan task is a task that is not a part of any swimlane (feature). In YouTrack terms, an orphan task is an issue of any type (except the issue type that is selected to identify swimlane), which is not linked to any issue of the "swimlane type" as a subtask.
Orphan tasks lane contains all the orphan tasks, that match the current sprint on the board. By default, the Orphans lane is located below all of the swimlanes. However, you can place the Orphans lane at the top of the board, via board's Settings.