With equal parts tedious paperwork and luck, you can stay in most countries for as long you have a valid visa.You'll find, however, that most countries offer U.S. citizens a reasonably long stay — at least as long as a moderate vacation or business trip — without all that messy paperwork and crazy amounts of proof of travel documents. Visa regulations vary widely by country, so you'll have to research your destination before you go to know how long you can stay.

Don't worry about staying too long and losing your U.S. citizenship. According to Customs and Border Protection, U.S. citizens can return at any time regardless of how long they've been abroad. If you’re considering staying for a while anywhere outside of the U.S. here are some general answers to FAQs.

For Work

If you're traveling to a foreign country to work, you'll need to obtain a work visa from your destination country.

The application process for a work visa can be challenging, especially in countries with struggling job markets; they would rather give jobs to their citizens.

Although if you're highly qualified and can provide a needed service, your chances for eligibility are much higher.

Once you get your work visa, most countries allow you to stay for the duration of the work.

The best way to approach getting a work visa is to contact the embassy and consulate of your country of origin within your destination country, as these departments usually have specific instructions for you to follow.

For Pleasure

Traveling for pleasure can be a little tricky depending on different countries’ laws. You can visit the United Kingdom for as long as six months with just a valid U.S. passport, but China almost always requires a visa to enter.

Even then, you're stuck with a small number of entries into the country. Some countries in the EU make it easy to travel between their borders. You can apply for a Schengen area visa, the most common visa for European travel. This visa allows travelers to cross freely into 27 Schengen countries, like Spain, Denmark, the Netherlands or Austria.

Read terms on this visa, as not all EU member states are part of the Schengen agreement. Notable members who are a part of the EU and not part of the Schengen Agreement include Ireland and Bulgaria.

Like applying for a work visa, it's always best to contact the consulate of your destination country to find out any special requirements for entering and how long you can stay.

For example, Argentina requires U.S. citizens to pay fees to enter the country. Most countries will allow you to stay for three months with the proper documents, but most also have exceptions to their rules.

For School

Studying abroad changes a lot of the rules for how long you can stay in another country. You're going to need a student visa and a school or program acceptance.

In general, countries are more lenient with doling out student visas because of student exchange agreements and the fact that many study abroad students decide to stay abroad and apply their newly acquired skills to the job markets in their countries of study.

Rules vary by country, but the U.S. government allows students to remain in the U.S. on an expired visa for as long as they maintain their student status.

However, if they travel outside of the U.S. to their home country, students must apply for a new visa or re-entry permit to return to their studies. Most countries allow students to stay for the duration of their studies on a student visa, with some requiring periodic renewals — usually every five or six months.

For Good

Although it is extremely difficult in most cases, retiring or moving permanently abroad is possible. If you're planning on becoming an expatriate, you'll likely have to try several avenues before you completely become a lawful permanent resident of your destination country.

You won't have any luck getting a retirement visa to many European countries or Canada because they don't allow these anymore. The countries that do allow retirement visas have made them difficult to obtain in many cases.

For example, Thailand has a policy of requiring retired expats to report to immigration services every 90 days as an example of the difficulties associated with retirement visas.

If you're not quite retired and simply want to move abroad, you'll have to jump through your destination country's hoops to become a green card holder or establish permanent residence.

Some countries, such as Italy, allow you to establish residency by renewing an extended visa every two years without working.

After five years, you can apply for a permanent resident permit and apply for the naturalization process five years after that. Permanent residency status requirements will vary by country and depend heavily on the country's current needs and immigration laws.