Types of Visas

Tourist Visa

This is the designation under which you'll find visas required for leisure travel. It covers the vast majority of visa applications.

Transit Visa

This is simply a short-duration visa (you're only meant to pass through the country) that is most often obtained in the same way as other visas, usually at a lower cost. Its validity is almost always less than a week. In practice, few countries offer such visas (Laos, Russia, Iran, Oman, etc.). So, if you're only staying for a very short time somewhere, always check the possibilities for a transit visa.

Note that in the case of an international air connection in an airport of a country requiring a visa, legally you don't need one as you're supposed to stay in the international transit zone. That said, this principle isn't accepted by all countries, starting with the United States, which requires an ESTA even if you're just in transit to another destination. In short, it's still better to always confirm with your airline or the competent authorities.

"Base Validity" and Visa Extension

Visa Usage Date

When a visa is issued, it can only be used up to a specific date. If you wish to enter the country after that date, your visa will have expired, and you risk being turned away (it will be considered that you don’t have a visa). Depending on the destination, visas are generally valid for use within one to three months after issuance.

Also, watch out for those whose "on-site" validity actually starts from the date of issuance rather than the date of actual entry into the country. However, if you think you’ll only exceed the deadline by a few days, ask to have it post-dated; some consulates do this without any issues.

Validity

While many countries offer only one validity period for their tourist visa, others provide a theoretical choice of durations, sometimes ranging from two weeks to several months. Depending on the duration, the application process (on arrival for 15 days, as in Bangladesh, or at consulates for longer stays) and costs can vary. Again, take only what you need.

Extension

Several countries allow, for a fee, visa renewals or extensions once you're in the country, ranging from a few days to several months. But be careful—nothing is systematic in this area, just as the validity granted during the application can vary. Occasionally, durations are decided on a case-by-case basis, especially at borders.

It’s always better to stay compliant to avoid trouble, from fines to imprisonment or even deportation.

Entry/Exit to a Neighboring Country

Also called a "Visa run." This is a practice used by some travelers (or residents) who want to stay longer in a country. Once their visa (or visa-free period) is nearly expired, they spend some time in a neighboring country before returning to benefit from a new stay. While this works for some destinations, it doesn’t for all or in every case.

Single or Multiple Entries

In addition to validity, the number of entries needed is also something to consider when applying. Some countries only allow one entry, while others offer a choice of single, double, or multiple entries (often for a slightly higher cost). Here too, it’s better to plan ahead, as for countries like Mongolia or Russia, such modifications on-site can lead to long, tedious, and complicated procedures.

Exit (or Entry) Visa (or Stamp)

This is quite rare and will only concern those traveling from one country to another by land, and often off the main routes. In fact, it’s the stamp (sometimes paid) that may be placed in your passport upon leaving the territory. At airports and major border posts, this usually happens automatically, and at worst, you’ll be directed to the right counter. However, in remote areas or where there’s a "no man’s land" between two countries, you may have to search for the office—or even the town (not necessarily on the border)—where you can complete this formality. Without it, you risk being turned away or fined by the customs of the neighboring country, with the obligation to retrieve the stamp. In some countries, it’s impossible to leave the territory without an exit visa.

Note that it’s also better to have your entry stamp (or date) in your passport. In its absence, some countries will fine you upon exit (e.g., $100 in Laos).

Special Permits

Not strictly a visa, though it functions similarly in practice. These permits concern specific regions of certain countries, mainly in Asia, such as India, Nepal, or Tibet. To access these areas, authorities must issue a special permit, often paid and time-limited, which may also sometimes require going through a local agency or even having an escort. While these permits are usually issued on-site, there’s nothing stopping you from inquiring beforehand with the consular services of the country in question.

Be careful, as these zones are generally regulated for domestic political reasons, so it’s advisable to respect the "procedures" to avoid heavy fines, deportation, or even imprisonment for non-compliance. This is even more critical if the regions are off-limits to foreigners.

Also worth noting is the case of Russia, where "insurance" is mandatory with the visa.

Registration with Authorities

Beyond the fact that this is mandatory in certain regions of a country, a few (rare) destinations also require travelers to register with the police upon arrival, despite having a visa. This is the case, for example, in Russia (outside transit) or some former USSR republics. Here too, it’s better to follow the procedure to avoid fines or deportation, even if in many cases, hoteliers handle this formality for their guests.