Germany is part of the Schengen agreement. The 26 Schengen countries are: Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, and Switzerland. If you can visit any of the above countries or have a visa for one you can travel to any other.
Bulgaria, Croatia, Cyprus and Romania are not technically Schengen countries but the same rules apply. However a visa from any of these four(4) countries may not allow you to enter the Schengen area.
Visas are not required by visitors from the following countries for visit up to 90 days in a 6 month period: Albania, Andorra, Antigua & Barbuda, Argentina, Australia, Austria, Bahamas, Barbados, Bosnia and Herzegovina, Brazil, Brunei, Canada, Chile, Colombia, Costa Rica, Dominica, El Salvador, Georgia, Grenada, Guatemala, Honduras, Hong Kong, Israel, Japan, Macau, Malaysia, Marshall Islands, Mauritius, Mexico, Monaco, Montenegro, New Zealand, Nicaragua, North Macedonia, Palau, Panama, Paraguay, Peru, Samoa, San Marino, Serbia, Seychelles, Singapore, Solomon Islands, South Korea, St Kitts and Nevis, Taiwan, Timor Leste, Tonga, Trinidad and Tobago, Tuvalu, Ukraine, United Arab Emirates, United Kingdom, United States, Uruguay, Vatican City and Venezuela.
Germany visa regulations
Germany is a member of the Schengen Countries