The backlog, called Not Started - Future Work by default, is a holding area for any work that is not in progress and is being considered for the future. The backlog is the furthermost top-level left lane of your board. You can subdivide the backlog into as many vertical sub-lanes and horizontal swimlanes as you like. You can view, edit, or move any cards in or out of the backlog as needed.
The Finished lane, called Finished - Ready to Archive by default when the board is first created, is a holding area for all cards that have been completed or discarded and is located on the right side of the board. You can subdivide the archive into as many vertical sub-lanes and horizontal swimlanes as you like.
Click on the expand/collapse icon to open and close any lane including the archive.
Opening the Finished lane will show cards added to the archive in the last 14 days. Cards that are older than 14 days are automatically added to the Finished Card Archive, accessible through the small icon in the upper right hand side of the lane’s header. Learn more about the Finished Card Archive here.