diff --git a/OAuth2.md b/OAuth2.md
index 1787491..a949ee2 100644
--- a/OAuth2.md
+++ b/OAuth2.md
@@ -154,7 +154,7 @@ export default Callback;
 
 
 
-# 3. Backend (Node.js): Handle Token Exchange
+# 3. [Backend] Exchange Code with Token 
 
 1. The backend receives the authorization `code` from the frontend,
 2. The backend makes a `POST` request to Google token endpoint, to exchange the authorization `code` for the `access_token` and optionally a `refresh token`
@@ -336,7 +336,7 @@ Authorization: Bearer access-token-from-backend
 </details>
 
 <details>
-<summary><h3>HTTP Request</h3></summary>
+<summary><h3>HTTP Response</h3></summary>
 
 ```json
 {
@@ -386,6 +386,34 @@ app.get('/api/user-profile', async (req, res) => {
 
 # 6. [Backend] Token Expiry and Refresh (Optional)
 
+<details>
+<summary><h3>HTTP Request</h3></summary>
+
+```bash
+POST https://oauth2.googleapis.com/token
+Content-Type: application/x-www-form-urlencoded
+
+grant_type=refresh_token&
+refresh_token=refresh-token-from-backend&
+client_id=YOUR_GOOGLE_CLIENT_ID&
+client_secret=YOUR_GOOGLE_CLIENT_SECRET
+```
+
+</details>
+
+<details>
+<summary><h3>HTTP Response</h3></summary>
+
+```json
+{
+    "access_token": "new-access-token",
+    "token_type": "Bearer",
+    "expires_in": 3600
+}
+```
+
+</details>
+
 <details>
 <summary><h3>Example Backend Code:</h3></summary>
 
@@ -422,6 +450,15 @@ app.post('/api/auth/refresh-token', async (req, res) => {
 
 
 
+
+
+
+
+
+
+
+
+
 ```sh
 GET https://xorismesiti.gr/callback?
     code=4/0AX4XfWgNmGZVbV7Kdr8Q9yVyzIYBnbbBdLfX39ZaE8m0w8zT8jKRLl7w-uT8k7WiyLg0Q&