diff --git a/sources/cas_server.php b/sources/cas_server.php
index e6ef560..226bf6f 100644
--- a/sources/cas_server.php
+++ b/sources/cas_server.php
@@ -1,15 +1,31 @@
 <?php
 
-$base_url = "/_matrix/cas_server.php";
+/*
+This is simple implementation of a CAS server to provide a SSO with synapse and Riot
+The authentication mecanisme is documented here: https://matrix.org/docs/spec/client_server/latest#sso-client-login
 
+Note that it's not a full implementation of a CAS server, but just the minimum to work with synapse and Riot.
+
+Mainly this CAS server will:
+1. Authenticate the user from the authentication header from ssowat
+2. Save the user authentication data in a php session
+3. Redirect the user to the homeserver (synapse)
+4. Answer to the homeserver if the user with a specific ticket number is authenticated and give his username.
+*/
+
+// Get the URL of the request
+$base_url = "/_matrix/cas_server.php";
 $url = explode('?', $_SERVER['REQUEST_URI'], 2)[0];
 
 switch ($url) {
+    // Request from the homeserver (synapse)
     case $base_url . "/proxyValidate":
+        // Get the session created by the client request
         session_id($_GET['ticket']);
         session_start();
-
+        // Check if this user was cleanly authenticated
         if ($_SESSION['user_authenticated']) {
+            // Give the authentication information to the server
             ?>
                 <cas:serviceResponse xmlns:cas="http://www.yale.edu/tp/cas">
                     <cas:authenticationSuccess>
@@ -29,11 +45,17 @@ switch ($url) {
         }
     break;
 
+    // First request from the client
     case $base_url . "/login":
+        // Generate a random number ticket which will be used by the client to authenticate to the server
         $ticket = bin2hex(random_bytes(50));
+
+        // Use the Ticket number as the session ID.
+        // This give the possiblity in the next request from the server to to find this session and the information related to.
         session_id($ticket);
         session_start();
 
+        // If the user is authenticated by ssowat save the username and set it as cleanly authenticated
         if (array_key_exists('REMOTE_USER', $_SERVER) && strlen($_SERVER['REMOTE_USER']) > 0) {
             $_SESSION['user_authenticated'] = true;
             $_SESSION['user'] = $_SERVER['REMOTE_USER'];
@@ -47,7 +69,6 @@ switch ($url) {
     break;
 
     case $base_url:
-
         header('Status: 302 Moved Temporarily', false, 302);
         header('Location: ' . $_GET['redirectUrl']);