diff --git a/3-Domain/src/main/java/user/Username.java b/3-Domain/src/main/java/user/Username.java
new file mode 100644
index 0000000..304e467
--- /dev/null
+++ b/3-Domain/src/main/java/user/Username.java
@@ -0,0 +1,5 @@
+package user;
+
+public record Username(String username) {
+	//TODO: checks if username is valid
+}