International travel documentation: Understanding passports and visas

International travel requires two primary documents: a passport and a visa. While a passport serves as official proof of citizenship issued by a traveler's home government, a visa is an entry permit issued by the destination country's authorities.

Passport cover colors—typically red, blue, green, or black—are not governed by a single international rule. Instead, countries choose colors based on national identity, history, geography, and politics. For example, red is common in Europe, while the United Kingdom changed its passport color following Brexit. Beyond aesthetics, passports must meet physical durability standards, including resistance to extreme temperatures and humidity.

Visas vary in format, including physical stamps or stickers, as well as electronic versions (e-Visas). Common categories include tourist, business, work, and student visas, each requiring specific documentation to comply with the destination country's immigration laws.