Travel compression socks have served savvy travelers well over the last few decades. Their ability to decrease leg pain on international flights is legendary. There are varying strengths of compression, ranging from 10-50 mmHg (millimeters of mercury). In most countries you can buy any compression socks over the counter that is 20 mmHg and under; anything over this amount will require a prescription from your doctor.
A word to the wise: compression socks should not be used by diabetics, as they will greatly increase blood circulation in your legs and feet ..
Travel compression socks real value is witnessed on long international flights, and once you begin using them, you'll never go back. I recommend packing two or three pairs on your next trip: one for the flight there, another for any time spent at altitudes over 3000 meters, and a third for any strenuous activities that may cause soreness on your legs (eg hiking, biking or jogging ).
If you purchased non-prescription strength travel compression socks, you can wear them all day; if you got them from your doctor, you should consult them regarding proper use. It is worth repeating that diabetics should not wear these socks.
Many travelers will also use compression socks when hiking, especially in high altitudes. It is safe to wear them throughout the day (if they are over the counter) and many people enjoy them even when they are not traveling.
Alright, enough about the health benefits, what about fashion? Do not sweat it; compression socks range from knee-high to ankle. Heck, they even sell pantyhose style socks now!