The borders can look very different from each other. While closely associated countries such as the Netherlands and the Belgium can be divided by a simple line on the roadway, the borders between countries with strong political tensions can be heavily fortified, such as the Korean Demilitarized Zone.
In general, there are three types of border controls:immigration, who checks people crossing the border, the customs, who checks the goods crossing the border and health checks. Depending on the political situation, none, one or the other, or all of the controls may be applied.
Types of controls
Immigration
These checks are done to see if you are allowed to enter the country. This will involve the verification and validity of your travel documents, passport, Visa, verification of the reasons given for entering the country and the duration of your stay. The questions you will be asked will depend on the type of stay you are planning: short-term tourist trip, work trip (short or long term), study trip, emigration or asylum application. Checks can also be carried out on your entire criminal and political history. At the borders of certain countries, a proof of travel to other countries may result in additional questions or you may simply be refused entry.
Customs
It checks that you do not import illegal goods into the country (eg protected animals and products derived therefrom, illegal drugs). Taxes or customs duties are paid there on certain products (for example, alcohol and luxury goods). It controls items that need a permit (eg firearms). Also be aware that some detection machines are very sensitive, so do not eat a bun covered in poppy seeds at Frankfurt airport before a flight to the Gulf countries (Opium is made from the poppy and the Most screening tests give false positives after consuming poppy seed). On cross-border ferries vehicles can be checked for possible stowaways.
The borders between the countries ofEU do not have customs controls at all in the classic sense. If you have goods that need to clear customs and the border is less strictly controlled such as between the Finland and the Norway, you may have to go to a customs office quite far from the border post, sometimes open only at certain specific times (only during the day, during office hours or when the ferry arrives ...).
You can thus be checked punctually, even long after crossing the border.
Sanitary control
In particular, vaccination certificates are checked there. These checks are more frequent in tropical countries where there are Infectious diseases like the yellow fever or in the event of an epidemic of Cholera.
To avoid the transfer of disease, food and plant products are generally not allowed to cross borders; this can often include things like an apple in a bag or firewood in your truck. Some health inspections are not linked to international borders. For example, all travelers between the California and Hawaii are subject to a fairly comprehensive agricultural inspection.
Location of controls
Immigration and customs controls are often located on either side of the border or in ports and airports. In some cases, it may not be directly located on the border. For example, passport control and UK customs for ferries and the Channel Tunnel are located on the French side before boarding; US government controls may be at the Canadian airport on flights to United States from Canada, (the same goes for some airports in Ireland, to United Arab Emirates and in Caribbean).
Customs controls can also occur where there is no national border, such as entering and leaving a free port area. Customs checks, often ad hoc, can also occur within a country, for example Germany frequently checks vehicles (especially foreign trucks) on highways. International rail links between European countries are a favorite location for immigration officials to do visa checks, even though there is no formal immigration check.
Free circulation
Some (usually neighboring) countries have agreements that allow travel between these countries without having to go through border control. The best known is theSchengen agreement which allows borderless travel between many (but not all) countries of theEuropean Union, the Swiss, the Norway, the'Iceland and the Liechtenstein.
the UK and theIreland, which are not members of Schengen, have a separate treaty of mutual free movement.
The Central American Free Movement Convention is a treaty between four countries ofcentral America (El Salvador, Guatemala, Honduras and Nicaragua) which allows the free movement of citizens and foreigners with a visa valid for one of these countries.