When you are making plans to travel to another foreign country, you have to take into account many things. Starting from whether you will be allowed to enter the country to where you will be staying a
If you are coming from a country which does not have a lot of free movement in foreign countries, then you will most likely need a visa.
This is the case for many non-EU nationals who want to enter the EU or Schengen zone countries. These people will need a Schengen visa to enter any of the participating countries. But getting a visa is a long process and you as an applicant will need many documents and steps to get it. One of the most important things you have to prove though is that you will not stay illegally in any of the Schengen zone countries. Because of this, having an invitation letter for the Schengen visa is extremely beneficial and will help your application a lot.