We're frequently asked how long is a bottle of wine still drinkable once it's been opened. The short answer: It depends on the wine.

Before we go over specific wines and how long you can expect them to stay delicious, it's important to understand why wine has a life cycle.
When wine is in the bottle, it goes through a process called micro-oxygenation.
Traces of oxygen permeate the closure and get to work on the organic molecules of the wine, slowly starting to ripen it and break it down.
The wine sees more micro-oxygenation every moment it's in the bottle and gets riper and more evolved every second until it finally hits a '"peak" of optimal drinkability. And once it peaks, it begins to decline very quickly.

Once a bottle of wine has been opened or uncorked, it's exposed too much more oxygen and therefore, the evolution process drastically speeds up. This is why you have a limited time to enjoy it at its peak of flavor and it's not actually harmful to consume.
As long as it tastes okay to you, feel free to drink it-just as in moments of desperation, a slightly brown avocado is better than no avocado.

Sparkling Wine: 1–3 days in the fridge with a sparkling wine stopper
Sparkling wines like Champagne, cava, and prosecco have the shortest enjoyment window-once the cork is popped, the bottle pressure that retains the bubbles dissipates and the wine turns flat. A sparkling wine stopper might help for a day or so, but it is recommended to drink sparkling wine the day you open it. Sparkling wines are widely available in half bottles and even single-serve "minis" for this reason: to prevent "leftovers" for solo or duo drinkers who just want a single glass.

Light White, Sweet White, and Rosé: 5–7 days in the fridge with a cork
Most light white and rosé wines will be drinkable for up to a week when stored in your refrigerator. You’ll notice the taste will change subtly after the first day, as the wine oxidizes. If you want a white wine that will last, your best bet is wines from cool-climate growing regions because those wines naturally have higher acidity. While lower-acid whites can last three to four days, high acidity will keep your wine fresh and vibrant for at least five days in the refrigerator. Famous examples of cool-climate white wines include Pinot Gris, Riesling, Chardonnay from Chablis in northern France, Pinot Grigio in Italy, and Sauvignon Blanc.

Full-Bodied White Wine: 3–5 days in the fridge with a cork
Full-bodied white wines, like oaked Chardonnay and Viognier, tend to oxidize more quickly because they saw more oxygen during their pre-bottling aging process. Be certain to always keep them corked and in the fridge.

Red Wine: 3–5 days in a cool dark place with a cork
For maximum lifespan in red wines after the bottle has been opened, choose wines that are higher in tannin. So, a light red with very little tannin, such as Pinot Noir, won’t last open as long as a rich red like Petite Sirah. Tannin is a compound found in the seeds, stems, and skins of grapes, and will help protect wine from oxygenation and lend a hand to age-ability. Some grape varietals have more natural tannin than others, and you will find these in red wine because white wines are made without using most of the skins and seeds. Wines with naturally higher tannin include cabernet sauvignon, syrah, and Nebbiolo. Low-tannin reds, like pinot noir and merlot, will last for two to three days but higher tannin wines should be delicious for up to five days after opening, as long as you treat them with care. Store open red wines in a chiller or a dark cool place after opening them. If you don’t have a chiller, your fridge is better than letting the wine sit out in a 70°F (21°C) room.

Fortified Wine: 28 days in a cool dark place with a cork
Fortified wines like Port have very long shelf lives because of the addition of brandy. While these wines do look marvelous displayed on a high shelf, they will lose their vibrant flavors more quickly from exposure to light and heat. Just so you know, the sweeter the dessert wine, the longer it will last open. The same temperature-based rules apply here: best to keep them stored in the fridge.

Source: Wine Folly - Martha Stewart - Enoteca