Visa

vi·sa

ˈvēzə/

noun

noun: visa; plural noun: visas

an endorsement on a passport indicating that the holder is allowed to enter, leave, or stay for a specified period of time in a country.

Origin

mid 19th century: via French from Latin visa, past participle (neuter plural) of videre ‘to see.’

So that’s what visa is! Do we really need it? Well, some countries think so. If you are curious, see how the state of the matter is right now around the globe: https://www.henleypassportindex.com

If you are a holder of U.S. passport:  Wikipedia Article

한국 여권 소지자의 경우: 무비자입국 가능국가

Good news for the U.S. citizens:

1. India now issues an eVisa. ( https://indianvisaonline.gov.in/evisa/tvoa.html )
2. China: You can get a 10-year multiple entry visa.
3. This leaves only Russia on the list of “Big 3 Hard to Get.”