This depends on your nationality. Some nationals of countries have to obtain a visa that grants them with the permission to enter the Schengen Area. The countries whose citizens are required to obtain a Schengen visa can be found on the visa page of the Schengen Visa Information.
Please note: Starting in May 2025, visitors from countries that do not need a visa to enter the Schengen Area will have to obtain a quick electronic entry authorization (ETIAS) before they can travel to an EU or Schengen country. This so called ‘ETIAS authorization‘ is not a visa, but rather a lighter and more visitor-friendly version. The application process for an ETIAS is simple and quick; it takes around 10 minutes to complete and costs only €7.