The passport is the basic credential for international travel. A U.S. passport is valid for ten years from the date of issuance. Besides a passport, many countries also require a visa. A visa is an endorsement placed on a passport, or on a document issued in lieu of a passport, by an official of the destination country. In most cases, a visa must be obtained from a consul representative in the country of residence prior to departure. Foreign consulates are found in major gateway cities, such as New York, San Francisco, and Los Angeles. A visa service can also handle the chore of obtaining a visa on behalf of a traveler or travel agent. Other types of entry documents may also be required, depending on the status of the traveler.

Visitors to some countries may be required to obtain a visitor's permit or tourist card at the point of entry. Usually, application forms are distributed to passengers on international flights. In some instances, applications must be obtained and completed on arrival at the airport or another point of entry. The entry permit or tourist card is stamped by a customs or immigration official as the passenger enters the country and must be kept in the bearer's possession during his or her stay. On departing, the traveler must present the permit to an official and, in some cases, pay an airport departure tax.

The value of most currencies fluctuates in relation to the currencies of other countries, often from one day to the next. A change in value affects the purchasing power of a tourist in a foreign country. For example, a hotel room with a nightly rate of 10,000 francs costs an American tourist $80 when the rate of exchange is 125 Tahitian francs per dollar. But when the rate falls to 100 francs per dollar, that same room costs the tourist $100 per night. The rate of exchange often influences travelers to visit countries where their purchasing power is greatest, or to put off visiting countries where the rate is unfavorable.

Many countries charge an airport tax or departure tax to help pay for the costs of operating the airport. The U.S. government charges an international passenger tax and, for arriving passengers, an additional customs fee.

Upon entry to a country, passengers must declare to a customs official all items purchased in a foreign country. Each country has a set limit on the value of merchandise that can be brought back into the country of residence. For example, travelers returning to the United States are allowed $400 worth of articles duty-free. The same or similar limits may apply to visitors who bring personal possessions into a destination country. For example, passengers entering Greece are limited to 200 cigarettes, five boxes of matches, two packs of playing cards, one liter of alcoholic beverages, and $150 worth of new articles purchased in a duty-free shop.

Customs limits vary from one country to another. Under certain circumstances, photographic equipment, clothing, jewelry, and other personal effects must be declared to a customs official on entering a foreign country. There are also limits on the amount of cash currency that may be brought into a country by foreign passengers. Such limits also often apply to currency taken out of the country by residents as well as visitors.

Tipping waiters, porters, taxicab drivers, and others who provide personal services to travelers is traditional in North America, but overseas, the practice varies considerably. In general, tipping is customary throughout Europe, Africa, and North and South America. Ten to 15 percent is considered customary for service in restaurants and hotels in most areas, although smaller tips are expected in South America. Porters are customarily tipped 50 cents to a dollar per bag. Taxi drivers in most parts of the world expect to be tipped 10 percent of the metered fare; if a set fee is charged, one to two dollars is considered adequate, depending on the total fare.

Tipping is less widespread in eastern Asia and Pacific regions outside Hawaii. In many Polynesian and Asian cultures, providing hospitality to strangers is considered an honor. In these societies, offering a tip to a host or hostess is insulting. Nevertheless, tipping has caught on in some areas of the South Pacific, particularly in Fiji and American Samoa. The practice is still discouraged in Tahiti and other islands of French Polynesia, and in China and Japan.

At many restaurants and lodging establishments around the world, a service charge equal to the amount of a reasonable tip is included in the bill. In such cases, additional tipping is not expected, but good manners dictates offering something extra for exceptional service.

Epidemics of malaria, cholera, tuberculosis and other diseases are widespread in many parts of Africa, Asia, and Malanesia. The National Institutes of Health or a health care professional should be consulted regarding current medical requirements for travel to these regions.