About the European Union
The European Union (EU) is a political and economic union of 27 Member States. Not all countries on the continent of Europe belong to the EU, however most of them do. EU combines certain characteristics of an international organization and a federal state. Many areas of life are regulated on EU-level (notably: trade and product quality/safety; agriculture and fishery; industry; telecom services), while the Member States retain sovereignty in many other regards (such as: taxes, employment, education, national security, governance, and elections). In practice, various state and EU regulations compliment each other, creating a complex and possibly unintuitive (from an outsider’s perspective) legislative mosaic.
What is more, certain areas are regulated with other international agreements, such as the Schengen Agreement ensuring that the borders are open between most of the European countries. There are also bilateral agreements between the EU and non-member states, as well as other international agreements, which regulate the flow of people, products and services in Europe.
The Schengen Area countries include: Austria, Belgium, Bulgaria, Denmark, Finland, France, Greece, Spain, Luxembourg, the Netherlands, Germany, Portugal, Romania, Sweden, Italy, Estonia, Lithuania, Latvia, Malta, Poland, the Czech Republic, Slovakia, Slovenia, Hungary, Croatia, as well as Liechtenstein, Switzerland, Norway and Iceland (the last four are non-EU Schengen countries). Ireland and Cyprus are EU-countries which do not belong to the Schengen area.
However, if you want to work during your non-visa stay, you are likely obliged to apply for a work permit. This is regulated internally.
Sources:
- https://mpra.ub.uni-muenchen.de/27179/1/MPRA_paper_27179.pdf
- https://migrant.poznan.uw.gov.pl/en/slownik-pojec/schengen-area-and-european-union