Visa-free countries are destinations that passport holders can enter without obtaining a visa beforehand. However, all travelers to visa-free countries must carry a valid passport or identity card to prove their nationality and identity throughout their journey. 

The rank of a passport (passport ranking) refers to the position that the passport occupies in the overall passport ranking index. Compared to the passports of other countries around the world, the strength of a passport depends on the total mobility score that the passport provides to its holders. This is measured by the total number of countries to which its passport holder can travel to, either without a visa (visa-free access), with a visa on arrival, or with an electronic travel authorization. The greater the number of these destinations, the higher the total points for freedom of movement, and therefore the stronger the passport. 

There are many types of passports, including ordinary passports, official passports, diplomatic passports, service passports, and emergency passports. 

You need a passport if you want to travel to another country. However, there are rare cases in which some countries allow citizens of other specific countries to enter their territory using only a national identification card (ID) instead of a passport. 

A visa is required if the country you are planning to visit demands that you obtain one prior to entry. 

A biometric passport or electronic passport is similar to an ordinary passport. The difference is that it contains a smart chip in its cover or on one of its pages, which includes the passport holder’s data. Biometric passports were created as a way to respond to the growing threat of identity theft and threats to national security.