Why visa is required?
Every country in this world has its own territory. No foreigner can enter without Visa. Entering a country without visa is against the law of that country’s immigration act. Visa is permission or a legal seal on a document to enter a country. Most of the visa is a stamp endorsed in the applicant's passport. Visa is required because no one is allowed to stay in a country without tax, payment and authorization.
Visa is required to know the background of a person who is applying for entry in a country. A person who has bad background or history is denied to get visa. The purpose is to avoid conflict, terrorism or any trouble may happen after this kind of dangerous person inside the country.
Visa is required to protect the population of a country. Thus immigration of a country is taking care of the issuing of visa. Most of the people from poor country want to enter into the rich country. Without visa, the authority will not know who is entering and there could be many problems with population. This may affect the economy or job for its own citizens.
Visa is issued with an expiry date. The authorization of time to stay is limited to know what did a person or foreigner and what is he doing, if a person is investing or working, he/she has to pay tax. Certification or clearance with passport is needed to apply with for visa extension. This is the way how visa is required. By having this visa, foreigner can go freely in to a country and immigration department also knows about why this foreigner is staying here. In case of problems, for the foreigner, visa is needed to show that he/she is staying legally. Finally visa is a good identity, legal stamp to stay and to go freely. For a country, visa is required to protect the country, its immigration law, people, economy and respect.