diff --git a/.idea/codeStyles/codeStyleConfig.xml b/.idea/codeStyles/codeStyleConfig.xml
new file mode 100644
index 0000000..a55e7a1
--- /dev/null
+++ b/.idea/codeStyles/codeStyleConfig.xml
@@ -0,0 +1,5 @@
+<component name="ProjectCodeStyleConfiguration">
+  <state>
+    <option name="PREFERRED_PROJECT_CODE_STYLE" value="Default" />
+  </state>
+</component>
\ No newline at end of file
diff --git a/src/validation.ts b/src/errors/exceptions.ts
similarity index 99%
rename from src/validation.ts
rename to src/errors/exceptions.ts
index 89bdf8b..bdbb7a2 100644
--- a/src/validation.ts
+++ b/src/errors/exceptions.ts
@@ -4,5 +4,4 @@
  *
  @example * `throw new ValidationError("Bad id")`
  */
-
 export class ValidationError extends Error {}
diff --git a/src/index.test.ts b/src/index.test.ts
index c7348f7..5c7f2dd 100644
--- a/src/index.test.ts
+++ b/src/index.test.ts
@@ -1,6 +1,6 @@
 import { assertStrictEquals } from "https://deno.land/std@0.87.0/testing/asserts.ts";
 import { sayHello, sayRandomHello } from "./index.ts";
-import { ID } from "./types.ts";
+import { ID } from "./types/id.ts";
 
 Deno.test("Random Hello", () => {
   const result = sayRandomHello();
diff --git a/src/index.ts b/src/index.ts
index 61fad20..e928749 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,5 +1,5 @@
 import { getLocaleById, localesSize } from "./repository/locales.ts";
-import { ID } from "./types.ts";
+import { ID } from "./types/id.ts";
 
 /**
  * Display the iconic Hello, World in a random locale
@@ -15,5 +15,5 @@ export const sayRandomHello = () => {
  * @param id Unique identifier
  */
 export const sayHello = (id: ID): string => {
-  return getLocaleById(id.id);
+  return getLocaleById(id.value);
 };
diff --git a/src/repository/data.ts b/src/repository/locales.data.ts
similarity index 100%
rename from src/repository/data.ts
rename to src/repository/locales.data.ts
diff --git a/src/repository/locales.ts b/src/repository/locales.ts
index 07c827d..bce13ed 100644
--- a/src/repository/locales.ts
+++ b/src/repository/locales.ts
@@ -1,4 +1,4 @@
-import { locales } from "./data.ts";
+import { locales } from "./locales.data.ts";
 
 export const localesSize = Object.keys(locales).length;
 
diff --git a/src/types.ts b/src/types.ts
deleted file mode 100644
index e548fe9..0000000
--- a/src/types.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-import { ValidationError } from "./validation.ts";
-import { localesSize } from "./repository/locales.ts";
-
-export class ID {
-  constructor(public id: number) {
-    this.#isValid(id);
-  }
-
-  #idIsValid = (id: number) => id > 0 && id < localesSize;
-
-  #isValid = (id: number) => {
-    if (!this.#idIsValid(id)) {
-      throw new ValidationError(`Invalid index: ${id}`);
-    }
-  };
-}
diff --git a/src/types.test.ts b/src/types/id.test.ts
similarity index 73%
rename from src/types.test.ts
rename to src/types/id.test.ts
index 395ff89..3346758 100644
--- a/src/types.test.ts
+++ b/src/types/id.test.ts
@@ -1,7 +1,7 @@
-import { ID } from "./types.ts";
-import { ValidationError } from "./validation.ts";
 import { assertThrows } from "https://deno.land/std@0.87.0/testing/asserts.ts";
-import { localesSize } from "./repository/locales.ts";
+import { localesSize } from "../repository/locales.ts";
+import { ID } from "./id.ts";
+import { ValidationError } from "../errors/exceptions.ts";
 
 Deno.test("ID validation fails for non strictly positive values", () => {
   assertThrows(() => new ID(-1), ValidationError, "Invalid index: -1");
diff --git a/src/types/id.ts b/src/types/id.ts
new file mode 100644
index 0000000..f4f84be
--- /dev/null
+++ b/src/types/id.ts
@@ -0,0 +1,20 @@
+import { localesSize } from "../repository/locales.ts";
+import { ValidationError } from "../errors/exceptions.ts";
+
+/**
+ * ID is the input type.
+ * It validates input value at creation
+ */
+export class ID {
+  constructor(public value: number) {
+    this.#validate(value);
+  }
+
+  #idIsValid = (id: number) => id > 0 && id < localesSize;
+
+  #validate = (id: number) => {
+    if (!this.#idIsValid(id)) {
+      throw new ValidationError(`Invalid index: ${id}`);
+    }
+  };
+}