A traveler's guide to maintaing your health on the road
Generally, you can drink the water in Europe (except on trains), North America (except Mexico), and Oceania (Australia and New Zealand). Anywhere else, stick to bottled water or treat the tap water with a sterlizing filter.
The hospitals in most developed countries (except in the U.S.) are marvels of socialized medicine, where for minor complaints or ailments you can often get taken care of lickety-split with no time spent in the waiting room, no forms to fill out, and no insurance co-pay.
Your home health insurance might work abroad, but probably not too well, so you may wish to consider buying travel health insurance.
For trips to the more exotic bits of Asia, Africa, and South America, there are some recommended vaccines, but few required ones.
That's the upshot. The page on general health concerns—and the rest of this section—will fill you in on all the details for keeping healthy while on the road.