When all the fermentation is over, the new wine is resting on all the dead yeast cells, called ‘lees’. The big or heavy lees are usually racked (drained off) off fairly quickly. Many winemakers choose to leave the new wine on the remaining ‘fine’ lees for a period of time – anything from a few weeks to several months and sometimes years. Ageing on the lees adds texture, palate weight and complexity to the wine. It also helps keep the wine fresh while waiting to be bottled.