To Rack (verb)
The action of moving wine (or any fermented liquid) off the sediment. In small scale production this is usually achieved syphoning the liquid down to the sediment but as the high end of the tube is placed above the sediment the syphoning process stops automatically before the sediment is sucked up.
Larger scale and professionals use conical fermenters, these have steeply sloped bottoms that collect the sediment, the very bottom is tapped to remove the sediment while leaving the wine in place. (see picture)