Storage methods that slow down the oxidation process in an open bottle of red wine, such as refrigeration or vacuum-storage, are better choices than just leaving the bottle out on your countertop. Your options range from no-cost and low-cost options, to wine savers with price tags of around $300, to wine refrigerators costing from $100 to $1,000.
Just as an apple turns brown when it's exposed to air, red wines react with oxygen, making them taste less robust and more bitter. At room temperature, oxidation takes place quickly. The advantage of countertop storage is that you can pour the wine immediately without letting it warm up from the cold temperatures of the refrigerator. But what you gain in time, you'll lose in flavor.
A full-bodied red wine, such as a cabernet or merlot, tastes fine when you leave it out for one day, but for multiple days and for lighter reds, such as pinot noir, refrigeration is a better choice. What's more, red wine can stain countertops; keep your bottle on a saucer or wine holder to reduce the chances of it spilling or leaking on your countertop.
The Wine Spectator website recommends that, ideally, you should store wine at a temperature of 55 degrees Fahrenheit, and serve it at that temperature too.
Your refrigerator, set to at least 40 F or cooler, keeps red wine too cold to serve immediately, but it does significantly slow down oxidation. Simply take the bottle out of the fridge about an hour before serving, or fill glasses about 20 minutes before serving to allow the wine to warm up slightly so its flavor and aroma peak. Red wine stays at its best in the refrigerator for about five days.
A wine bottle won't leak stored on its side if you've removed the cork without puncturing it. If the cork has a hole in it, store the bottle standing upright instead.
Wine vacuum tools suck most of the air from an open bottle of wine or insert argon gas into the bottle displacing oxygen; both methods significantly reduce oxidation. Some models come with their own plug and pump, while others use a needle inserted into the cork itself. The editors at _Cook's Illustrated_ reported on their website that opened bottles of red wine tasted as fresh after one month as newly opened bottles.