Color is the first giveaway.

Nations tend to pick colors that reflect their national character.

New Zealand decorates its famous rugby team,

its airline, and its passports

in the nation's favorite color, black.

Many Islamic countries have green passports

because of the importance of the color in the Muslim faith.

But as well as a statement of national identity,

color can demonstrate international cooperation.

The British passport was originally a regal navy blue.

But after Britain joined the European Union in 1973, it switched to Burgundy red in line with other EU countries.

The common color was supposed to make

European passports instantly recognizable.

But since colors can't be patented,

nothing stops others with the same idea.

A number of countries that aspire to join the EU

have changed their passports to Burgundy too.

Meanwhile, Britain has decided to leave the club.

Its government has announced that the UK passports

will revert back to navy blue after Brexit.

If you have a passport from Singapore or South Korea,

you're in possession of one of the most powerful travel documents on earth.

Passport power is measured by the number of countries the holder can access visa-free.

Currently sharing first place in the power rankings,

Singaporean and South Korean passports

provide visa-free access to 162 countries each.

British passport holders share fourth place

in the power ranking with six other nations,

each accessing 159 countries visa-free.

Americans rank fifth with access to 158.

Somalia, Syria, Pakistan, and Iraq

are among the world's least powerful passports.

Afghanistan is the lowest-ranking of all,

with visa-free access to just 26 countries.

Having to get a visa is a hassle.

First, there is the never-ending form.

Then there are lengthy appointments and expensive fees.

Some visas also require travelers to pre-book flights

to prove that they intend to return home.

But there are unexpected upsides

to some of the world's weaker passports.

Middle-ranking Namibia is one of just a handful of countries whose citizens can enter Angola visa-free.

India is one of only three countries

whose citizens have visa-free access into Bhutan.

A low-ranking passport limits your choices,

but not your sense of adventure.