diff --git a/backend/controllers/tasksController.js b/backend/controllers/tasksController.js
index 745738d..2f1e314 100644
--- a/backend/controllers/tasksController.js
+++ b/backend/controllers/tasksController.js
@@ -3,6 +3,11 @@ const path = require('path');
 const { v4: uuidv4 } = require('uuid');
 
 const filePath = path.join(__dirname, '../data/tasks.json');
+const VALID_CATEGORIES = ['High', 'Medium', 'Low'];
+
+function normalizeCategory(category) {
+  return VALID_CATEGORIES.includes(category) ? category : 'Medium';
+}
 
 function readTasks() {
   return JSON.parse(fs.readFileSync(filePath, 'utf-8'));
@@ -18,8 +23,12 @@ exports.getAllTasks = (req, res) => {
 
 exports.createTask = (req, res) => {
   const tasks = readTasks();
-  const { title, completed = false } = req.body;
-  const newTask = { id: uuidv4(), title, completed };
+  const { title, completed = false, category = 'Medium' } = req.body;
+  if (typeof title !== 'string' || title.trim() === '') {
+    return res.status(400).json({ message: 'Title is required and cannot be empty' });
+  }
+  const normalizedCategory = normalizeCategory(category);
+  const newTask = { id: uuidv4(), title: title.trim(), completed, category: normalizedCategory };
   tasks.push(newTask);
   writeTasks(tasks);
   res.status(201).json(newTask);
@@ -30,8 +39,16 @@ exports.updateTask = (req, res) => {
   const task = tasks.find(t => t.id === req.params.id);
   if (!task) return res.status(404).json({ message: 'Task not found' });
 
-  task.title = req.body.title ?? task.title;
+  if (req.body.title !== undefined) {
+    if (typeof req.body.title !== 'string' || req.body.title.trim() === '') {
+      return res.status(400).json({ message: 'Title is required and cannot be empty' });
+    }
+    task.title = req.body.title.trim();
+  }
   task.completed = req.body.completed ?? task.completed;
+  if (req.body.category !== undefined) {
+    task.category = normalizeCategory(req.body.category);
+  }
   writeTasks(tasks);
   res.json(task);
 };
diff --git a/frontend/index.html b/frontend/index.html
index 915426f..4291634 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -14,6 +14,11 @@ <h1>Task List</h1>
   </div>
   <form id="taskForm">
     <input type="text" id="taskInput" placeholder="New task" required />
+    <select id="taskCategory" aria-label="Task category">
+      <option value="High">High</option>
+      <option value="Medium" selected>Medium</option>
+      <option value="Low">Low</option>
+    </select>
     <button type="submit" title="Click to add a new task to the list">Add Task</button>
   </form>
   <ul id="taskList"></ul>
diff --git a/frontend/script.js b/frontend/script.js
index a519ccf..e7cc9e2 100644
--- a/frontend/script.js
+++ b/frontend/script.js
@@ -1,7 +1,9 @@
 const API_URL = 'http://localhost:3000/api/tasks';
+const DEFAULT_CATEGORY = 'Medium';
 const taskList = document.getElementById('taskList');
 const taskForm = document.getElementById('taskForm');
 const taskInput = document.getElementById('taskInput');
+const taskCategory = document.getElementById('taskCategory');
 const themeToggle = document.getElementById('themeToggle');
 
 // Theme functionality
@@ -35,28 +37,54 @@ async function fetchTasks() {
 }
 
 function addTaskToDOM(task) {
+  const category = task.category || DEFAULT_CATEGORY;
   const li = document.createElement('li');
-  li.innerHTML = `
-    <span class="${task.completed ? 'completed' : ''}">${task.title}</span>
-    <div>
-      <button onclick="toggleComplete('${task.id}', ${!task.completed})">✓</button>
-      <button onclick="deleteTask('${task.id}')">✕</button>
-    </div>
-  `;
+  const taskContent = document.createElement('div');
+  taskContent.className = 'task-content';
+
+  const title = document.createElement('span');
+  title.className = `task-title ${task.completed ? 'completed' : ''}`;
+  title.textContent = task.title;
+
+  const badge = document.createElement('span');
+  badge.className = `category-badge category-${category.toLowerCase()}`;
+  badge.textContent = category;
+
+  const actions = document.createElement('div');
+
+  const completeButton = document.createElement('button');
+  completeButton.textContent = '✓';
+  completeButton.setAttribute('aria-label', task.completed ? 'Mark task as incomplete' : 'Mark task as complete');
+  completeButton.addEventListener('click', () => toggleComplete(task.id, !task.completed));
+
+  const deleteButton = document.createElement('button');
+  deleteButton.textContent = '✕';
+  deleteButton.setAttribute('aria-label', 'Delete task');
+  deleteButton.addEventListener('click', () => deleteTask(task.id));
+
+  taskContent.appendChild(title);
+  taskContent.appendChild(badge);
+  actions.appendChild(completeButton);
+  actions.appendChild(deleteButton);
+  li.appendChild(taskContent);
+  li.appendChild(actions);
   taskList.appendChild(li);
 }
 
 taskForm.addEventListener('submit', async e => {
   e.preventDefault();
-  const title = taskInput.value;
+  const title = taskInput.value.trim();
+  if (!title) return;
+  const category = taskCategory.value || DEFAULT_CATEGORY;
   const res = await fetch(API_URL, {
     method: 'POST',
     headers: { 'Content-Type': 'application/json' },
-    body: JSON.stringify({ title })
+    body: JSON.stringify({ title, category })
   });
   const task = await res.json();
   addTaskToDOM(task);
   taskInput.value = '';
+  taskCategory.value = DEFAULT_CATEGORY;
 });
 
 async function toggleComplete(id, completed) {
diff --git a/frontend/style.css b/frontend/style.css
index d351594..65e6af1 100644
--- a/frontend/style.css
+++ b/frontend/style.css
@@ -88,7 +88,8 @@ form {
   gap: 12px;
   margin-bottom: 1.5em;
 }
-#taskInput {
+#taskInput,
+#taskCategory {
   flex: 1;
   padding: 0.75em 1em;
   border: none;
@@ -100,7 +101,8 @@ form {
   outline: none;
   transition: box-shadow 0.2s;
 }
-#taskInput:focus {
+#taskInput:focus,
+#taskCategory:focus {
   box-shadow: 0 2px 8px var(--input-focus-shadow);
 }
 button[type="submit"] {
@@ -138,12 +140,39 @@ li {
 li:hover {
   box-shadow: 0 4px 16px var(--task-hover-shadow);
 }
-li span {
+.task-title {
   font-size: 1.05em;
   flex: 1;
   color: var(--text-color);
   transition: color 0.2s;
 }
+.task-content {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  flex: 1;
+}
+.category-badge {
+  display: inline-block;
+  width: fit-content;
+  padding: 0.15em 0.6em;
+  border-radius: 999px;
+  font-size: 0.75em;
+  font-weight: 500;
+  line-height: 1.4;
+}
+.category-high {
+  background: #ffebee;
+  color: #8b0000;
+}
+.category-medium {
+  background: #fff8e1;
+  color: #8a3b00;
+}
+.category-low {
+  background: #e8f5e9;
+  color: #1b5e20;
+}
 .completed {
   text-decoration: line-through;
   color: var(--completed-color);