There's a significant reason behind the four standard colors found on passports—but there are some unusual shades, too.

UK passports have recently changed colour from red to blue following Brexit but what do the colours of passports mean? As well as red and blue, you might also come across green and black passports ...

Passport cards are objects that look much like US driver's licenses and can be kept in your wallet. They allow for travel from the US by land or sea to Canada, Mexico or Caribbean countries.