Wine hates heat; anything above 70° Fahrenheit wreaks havoc on the wine. 55° Fahrenheit is the ideal temperature, but don’t freak out if it varies a degree or two either way. Humidity is also important; the proper humidity keeps the cork from drying out and letting oxygen seep into the bottle. Oxygen will oxidize a wine, the same way it will a peeled apple. A brown apple is unattractive, but edible; an oxidized wine is not drinkable. It won’t hurt you, unless it’s truly spoiled, but it won’t taste good at all.
Wine hates sunlight like a vampire, and pretty much for the same reason: light, particularly UV light, prematurely ages wine. Whites are more susceptible than reds, but reds fall victim to UV light as well. Ever wonder why wine is sold in colored bottles? The colored glass acts like sunglasses, and filters the UV light out.
Why would wine care if you shook the bottle? Two reasons: too much shaking can prematurely age it, and not in a good way, and if the wine is a red, sediment gets disturbed from the bottom and distributed around the bottle. The result is a glass of grit instead of a glass of wine. So don’t store your wine where vibrations, good or bad, abound.
There are two good reasons for storing wine on its side: first, storing the bottle this way keeps the cork in contact with the wine and this keeps the cork from drying out and shrinking. A dry cork allows oxygen in, and this is not a good thing. Second, storing wine horizontally saves space, letting you keep more bottles in a smaller space.
Given that most of us don’t have a wine cellar already built into our house, where should you store your wine? If you have a basement, and dampness is not an issue, putting wine racks in a cool, dark corner fits the bill nicely. If a basement is not an option, use a cool, dark closet. If the closet is too hot, you can get a cooling unit designed for wine to cool things off.