diff --git a/src/main/java/de/hs_mannheim/domain/System.java b/src/main/java/de/hs_mannheim/domain/System.java
new file mode 100644
index 0000000..29f7ab5
--- /dev/null
+++ b/src/main/java/de/hs_mannheim/domain/System.java
@@ -0,0 +1,30 @@
+package de.hs_mannheim.domain;
+
+import java.util.HashSet;
+
+public class System {
+    
+    private User current_user;
+
+    public HashSet<User> get_all_user(){
+        return new HashSet<User>();
+    }
+
+    public boolean sign_in_user(String username, String password){
+        return true;
+    }
+
+    public boolean sign_up_user(String username, String password, String hometown, int zip, 
+                                String car_name, double car_co2_km, double car_avg_kmh, double bike_avg_kmh){
+        return true;
+    }
+
+    public void sign_out_user(){}
+
+    public boolean change_user_details(String username, String password, String hometown, int zip, 
+                                String car_name, double car_co2_km, double car_avg_kmh, double bike_avg_kmh){
+        return true;
+    }
+
+}
+