EXPAT FAQ
https://www.easyexpat.com/en/faq.htm
What is a Schengen Visa?
Since 26th March 1995, a new type of visa - the Schengen Visa - has been introduced by the following member-states of the European Union who are signatories of the Schengen Agreement: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Italy, Luxembourg, The Netherlands, Norway, Portugal, Spain, Sweden.
The Schengen visa issued by an Embassy or Consulate of the above countries allows the holder to move freely in all of these countries within the validity of the visa.
You must ask a visa for multiple entries. It's usually valide for period of 1, 3 monthhs or more.
In order to apply you need to go to the embassy of one of the Schengen country.
More information here: https://www.schengenvisainfo.com/.