You've just landed in Beijing, Rio de Janeiro or Christchurch, New Zealand, and you're greeted at the airport by a clutch of adoring locals.
What is the polite way to greet them? Do you bow, or proffer your hand, or prepare to envelop the assembled strangers in an American-style embrace?
More important: To kiss or not to kiss?
The world may be increasingly globalised, but when it comes to greeting practices, local customs still prevail – and things can get awkward when, say, a hug-loving American businessman meets his Japanese counterpart for the first time. (Best just to bow.)
If you find yourself facing a group of native Maoris in New Zealand, you'll want to steel yourself for a traditional nose greeting, which involves touching snouts to one another's foreheads.
In India, a limp handshake between men is fine, but don't try it with the opposite sex.
In Rio, local convention dictates three cheek kisses. But a few hours' drive to the south in Sao Paulo, the single peck prevails.
In Beijing, the locals prefer a nod and a smile.
In the interests of international fellowship and peace, here is an incomplete guide to world greetings.
In much of Latin America, Europe and the Middle East, air kissing between strangers is common, but each nation, and in some cases each region within a country, may have its own habits.
Argentine men will cheek-kiss one another, but only if they are friends of friends. In most of the Arab world, a double air kiss is obligatory, though only between people of the same sex.
Things can get complicated in France. Expect anywhere from four kisses (in Nantes) down to two (in Toulouse) or just a single peck (in Brest). The general rule is that lips should never touch cheek, though a faint smooching sound is expected.
In most of Northern Europe, a firm handshake will usually suffice between strangers, and a single kiss for friends.
"Firm" doesn't begin to describe the obligatory handshake between two unacquainted men in Russia, which can feel like a test of strength with near bone-crushing results.
And there's a taboo about shaking hands across the threshold of a home: Wait until you are both on the same side of the door.
When kisses are called for, where do you aim? In Portugal, the kissing usually progresses from left to right, but in Strasbourg, France, it's right to left.
Hands to yourself
Kissing or touching strangers is frowned upon in Asia.
The customary greeting in Thailand involves a bow with the palms pressed together, as if in prayer; similar gestures are common from Cambodia to Indonesia.
In India, a limp handshake between men is fine, but don't try it with a member of the opposite sex. The traditional way to greet an Indian elder is to bend down and touch his feet.
Tibetans have one of the most unusual traditional gestures for greeting others: They stick out their tongues, though always from a safe distance.
What are the rules of greeting people in Australia? Let us know in the Comments section.
The New York Times