A visa is an official document that contains all your information. This document explains the purpose of your visit, and it is the one document without which you will not be allowed to travel or visit most of the countries. The immigration department and the country's policies oblige you to follow these rules and regulations. While some countries provide you with a visa on arrival, most of the countries have a strict protocol that states that you cannot enter their boundaries without a legitimate visa. All these factors make this document one of the most critical components that you need to have.