Maybe it's something that you haven't noticed. On a vacation, sometimes that mini-fridge in your hotel room doesn't get used much — but if you're counting on it to keep your frozen vegetables cold or your medication at its specified storage temp, knowing how cold the fridge gets is pertinent information.

The U.S. Food and Drug Administration recommends that you keep your fridge at or below 40°F (4°C). They recommend your freezer temperature be at 0°F (-18°C). These aren't just suggestions you should think about following — food is less likely to spoil and build harmful bacteria at these temperatures. This includes leftovers and "doggie bags" that you take home from restaurants.

Temperatures higher than those advised by the FDA put your food at risk of being in the "danger zone." According to the U.S. Department of Agriculture, the "danger zone" is a range of temperatures between 40°F and 140°F. These are prime temperatures for bacteria to grow and multiply at their fastest.