Deck is one of the available UI types.By displaying several views called "Columns" next to another, it provides high customizability and can display high amounts of information at once.
You can switch the positions of two columns via drag-and-dropping them or change a column's position from its column menu (accesible by right-clicking the column header).
Columns can not only be arranged vertically, but also horizontally. If you click "Stack on left column" when opening the column menu, the column will be moved below the column to the left of the current one. To cancel the stacking, press the "Pop to the right" button in the column menu.