Storage is an important consideration for wine that is being kept for long-term aging. While most wine is consumed within 24 hours of purchase, fine wines are often set aside for long-term storage. Wine is one of the few commodities that can improve with age but it can also rapidly deteriorate if kept in inadequate conditions. The three factors that have the most direct impact on a wine's condition are light, humidity and temperature. A fourth consideration is security for expensive wines. Historically the storage of wine was handled by wine merchants but since the mid-20th century consumers have been increasingly storing their own wine in home-based wine cellars.