Because leftovers only remain safe to eat for four days, you’re going to want to eat up all your turkey, stuffing and gravy by Monday.

(The importance of Thanksgiving leftovers as immortalized in pop culture by  Friends Moistmaker episode)

Ideally, you should freeze all leftovers as soon as possible, but if you throw the rest in freezer-safe bags or containers, it will be good to eat for another six months.

Actually, food technically remains safe to eat forever if it’s frozen, it just loses flavor and moisture.

The USDA wrote these guidelines for safely reheating stored leftovers:

• When reheating leftovers, be sure they reach 165° F. Use a food thermometer to check the internal temperature of the food. Reheat sauces, soups and gravies by bringing them to a rolling boil. Cover leftovers to reheat. This retains moisture and ensures that food will heat all the way through.
• Thaw frozen leftovers safely in the refrigerator, cold water or the microwave oven. When thawing leftovers in a microwave, continue to heat it until it reaches 165 °F as measured with a food thermometer.
• Any leftover “leftovers” thawed by the cold water method or in the microwave should be reheated to 165 °F before refreezing.
• In a real hurry? It is safe to reheat frozen leftovers without thawing, either in a saucepan or microwave (in the case of a soup or stew) or in the oven or microwave (for example, casseroles and combination meals). Reheating will take longer than if the food is thawed first, but it is safe to do when time is short.

I don’t know about you, but I certainly never knew to reheat my sauces to a full boil…oops.
Make sure to occasionally stir foods when microwaving them, because foods won’t heat evenly (especially if you don’t have a turntable) and cold spots will develop in which bacteria hasn’t been properly killed.