The cooled beer is allowed to stand in the FV for 2 - 3 days, during which time much of the now inactive yeast remaining in the beer after skimming sinks to the bottom of the FV. The beer can then be run into casks, a process known as racking.
During racking a biological clarifyer called finings is added to the casks. The finings causes the yeast remaining in the beer to form into clumps which then sink to the bottom, leaving clear beer in the cask.