diff --git a/index.php b/index.php
new file mode 100644
index 0000000..3d33f72
--- /dev/null
+++ b/index.php
@@ -0,0 +1,107 @@
+<?php
+session_start();
+
+// Initialize the to-do list if it doesn't exist
+if (!isset($_SESSION['todo_list'])) {
+    $_SESSION['todo_list'] = [];
+}
+
+// Add new Task
+if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['new_todo'], $_POST['priority'])) {
+    $new_todo = trim($_POST['new_todo']);
+    $priority = $_POST['priority'];
+    if ($new_todo !== '') {
+        $_SESSION['todo_list'][] = [
+            'task' => $new_todo,
+            'priority' => $priority,
+            'done' => false
+        ];
+    }
+}
+
+// Mark Task done or undone
+if (isset($_GET['toggle'])) {
+    $index = intval($_GET['toggle']);
+    if (isset($_SESSION['todo_list'][$index])) {
+        $_SESSION['todo_list'][$index]['done'] = !$_SESSION['todo_list'][$index]['done'];
+    }
+}
+
+// Delete Task
+if (isset($_GET['delete'])) {
+    $index = intval($_GET['delete']);
+    if (isset($_SESSION['todo_list'][$index])) {
+        array_splice($_SESSION['todo_list'], $index, 1);
+    }
+}
+
+// Sort by priority (high -> medium -> low)
+usort($_SESSION['todo_list'], function($a, $b) {
+    $priorityOrder = [
+        'high' => 3,
+        'medium' => 2,
+        'low' => 1
+    ];
+    return $priorityOrder[$b['priority']] <=> $priorityOrder[$a['priority']];
+});
+?>
+
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>To-Do List</title>
+    <!-- Bootstrap CSS -->
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/css/bootstrap.min.css" rel="stylesheet">
+</head>
+<body>
+<div class="container mt-5">
+    <h1 class="text-center">To-Do List</h1>
+    <div class="card">
+        <div class="card-body">
+            <form action="index.php" method="POST">
+                <div class="input-group mb-3">
+                    <input type="text" class="form-control" name="new_todo" placeholder="Add a new task" aria-label="Add a new task" required>
+                    <select class="form-select" name="priority">
+                        <option value="high" selected>High Priority</option>
+                        <option value="medium">Medium Priority</option>
+                        <option value="low">Low Priority</option>
+                    </select>
+                    <button class="btn btn-primary" type="submit">Add</button>
+                </div>
+            </form>
+            <ul class="list-group">
+                <?php foreach ($_SESSION['todo_list'] as $index => $item): ?>
+                    <?php
+                        $priorityClass = '';
+                        switch ($item['priority']) {
+                            case 'high':
+                                $priorityClass = 'list-group-item-danger';
+                                break;
+                            case 'medium':
+                                $priorityClass = 'list-group-item-warning';
+                                break;
+                            case 'low':
+                                $priorityClass = 'list-group-item-success';
+                                break;
+                        }
+                        $doneClass = $item['done'] ? 'text-decoration-line-through' : '';
+                    ?>
+                    <li class="list-group-item d-flex justify-content-between align-items-center <?php echo $priorityClass; ?>">
+                        <span class="<?php echo $doneClass; ?>"><?php echo htmlspecialchars($item['task']); ?></span>
+                        <div>
+                            <a href="?toggle=<?php echo $index; ?>" class="btn btn-sm btn-outline-secondary">
+                                <?php echo $item['done'] ? 'Undone' : 'Done'; ?>
+                            </a>
+                            <a href="?delete=<?php echo $index; ?>" class="btn btn-sm btn-danger">Delete</a>
+                        </div>
+                    </li>
+                <?php endforeach; ?>
+            </ul>
+        </div>
+    </div>
+</div>
+<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/js/bootstrap.bundle.min.js"></script>
+</body>
+</html>
