Delicious for drinking with food, dry red wines (dry meaning they have less sugar) are also useful in cooking. As with white wines, the acidity in red wine will punch up other flavors in the dish, provided there's not too much tannin (that bitter flavor that makes your mouth pucker) or oak (that toasty vanilla flavor from aging in oak barrels) to overshadow the food. Red wine is delicious as part of the liquid for braising or stewing (think beef Burgundy). It's also wonderful for deglazing pans to make a pan sauce for seared lamb, duck, chicken, or beef. You can even use red wine for flavoring desserts.
Port can often be used in place of red wine in pan sauces, but it usually comes with a higher price tag.
Avoid at all cost the "cooking wine" at the supermarket; instead, choose something you wouldn't mind drinking—ideally, a wine you'd pair with whatever you're cooking. The best red wines for cooking are those with moderate tannins: Merlot, Pinot Noir, Sangiovese (the main grape in Chianti), and lighter-style Cabernets. Heat won't improve the undesirable qualities of bad wine: it will accentuate them. Conversely, heat kills the subtle nuances in a complex wine, so save the really good stuff for drinking. In general, go for young wines with lively fruit notes for the best flavor in the pot or pan.
Because wine also contains alcohol, you usually add it at the start of cooking so the alcohol has a chance to burn off. Splashing wine into a dish at the end of cooking usually results in an unpleasant raw-wine taste.
Store unopened bottles in a dark, cool, place. Once opened, wine will begin to oxidize, which adversely affects flavor. Recork opened bottles and refrigerate them to slow down the process; try to finish off an opened bottle within a few days.