A visitor visa is applicable in cases where you want to migrate to the country for a shorter time period for any reason such as business meetings, travel to visit the family, etc. All countries follow different routes to provide and accept visitor visas along with the distinct requirements of the documents. 

The basic route to apply for the visitor visa however usually starts with filling out the form and submitting it along with the various documents required. There are several immigration agencies that can help you with this part as some of the countries include certain terms and conditions like owning a valid travel document, being in stable health, having zero criminal or immigration-related convictions, etc. 

The documents required in common to almost all countries include a passport, proof of several other identification documents of both the individual and the person involved in the travel such as a spouse, children, etc., flight tickets, proof of citizenship, etc.