A magnum is a large bottle used for storing wine or champagne, typically holding 1.5 liters, which is equivalent to two standard bottles. This size is popular for special occasions and celebrations, as it allows for a greater volume of wine, enhancing the experience of sharing. Magnums are often associated with higher quality wines, as they age more slowly than smaller bottles, allowing for better development of flavors. They are commonly used for red wine, white wine, and sparkling wine, making them a versatile choice for both casual gatherings and formal events.