diff --git a/build/build.js b/build/build.js
index 94ef81a..2bd0892 100644
--- a/build/build.js
+++ b/build/build.js
@@ -36,7 +36,7 @@ const config = {
 
     // File processing order (dependency-aware)
     cssOrder: ['base.css', 'layout.css', 'components.css', 'themes.css', 'prism.css'],
-    jsOrder: ['prism-core.js', 'navigation.js', 'progress.js', 'code-blocks.js', 'quiz.js', 'main.js'],
+    jsOrder: ['prism-core.js', 'navigation.js', 'progress.js', 'code-blocks.js', 'quiz.js', 'search.js', 'main.js'],
 
     // Template placeholders
     placeholders: {
diff --git a/src/index.html b/src/index.html
index f1e1bba..e790fa3 100644
--- a/src/index.html
+++ b/src/index.html
@@ -19,6 +19,32 @@
                 <h2>RESTful API Design</h2>
                 <p>7-Day Learning Module</p>
             </div>
+
+            <!-- Search -->
+            <div class="search-container">
+                <div class="search-input-wrapper">
+                    <svg class="search-icon" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+                        <circle cx="11" cy="11" r="8"></circle>
+                        <path d="m21 21-4.35-4.35"></path>
+                    </svg>
+                    <input
+                        type="text"
+                        id="search-input"
+                        class="search-input"
+                        placeholder="Search topics..."
+                        autocomplete="off"
+                        aria-label="Search course content"
+                    />
+                    <button id="search-clear" class="search-clear" style="display: none;" aria-label="Clear search">
+                        <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+                            <line x1="18" y1="6" x2="6" y2="18"></line>
+                            <line x1="6" y1="6" x2="18" y2="18"></line>
+                        </svg>
+                    </button>
+                </div>
+                <div id="search-results" class="search-results" style="display: none;"></div>
+            </div>
+
             <div id="nav-container"></div>
         </nav>
 
diff --git a/src/scripts/main.js b/src/scripts/main.js
index f796887..450907b 100644
--- a/src/scripts/main.js
+++ b/src/scripts/main.js
@@ -32,7 +32,7 @@ function loadTheme() {
 
 /**
  * Initialize the application when DOM is ready
- * Sets up theme, loads progress, renders navigation, and initializes code blocks
+ * Sets up theme, loads progress, renders navigation, initializes code blocks, and search
  */
 document.addEventListener('DOMContentLoaded', () => {
     loadTheme();
@@ -40,4 +40,5 @@ document.addEventListener('DOMContentLoaded', () => {
     renderNav();
     updateProgress();
     initializeCodeBlocks();
+    initializeSearch();
 });
diff --git a/src/scripts/search.js b/src/scripts/search.js
new file mode 100644
index 0000000..b704fa0
--- /dev/null
+++ b/src/scripts/search.js
@@ -0,0 +1,386 @@
+// ============================================================
+// SEARCH MODULE
+// Provides search functionality across all day content
+// Features: Real-time search, highlighting, result navigation
+// ============================================================
+
+let searchIndex = null;
+let currentResults = [];
+let currentResultIndex = -1;
+
+/**
+ * Initialize search functionality
+ * Builds search index from all day content
+ */
+function initializeSearch() {
+    buildSearchIndex();
+
+    const searchInput = document.getElementById('search-input');
+    const searchClear = document.getElementById('search-clear');
+
+    if (searchInput) {
+        // Real-time search as user types
+        searchInput.addEventListener('input', debounce(handleSearch, 300));
+
+        // Handle Enter key to navigate results
+        searchInput.addEventListener('keydown', (e) => {
+            if (e.key === 'Enter') {
+                e.preventDefault();
+                navigateToNextResult();
+            }
+        });
+    }
+
+    if (searchClear) {
+        searchClear.addEventListener('click', clearSearch);
+    }
+}
+
+/**
+ * Build search index from all day content
+ * Creates a searchable database of all text content with location info
+ */
+function buildSearchIndex() {
+    searchIndex = [];
+
+    const days = document.querySelectorAll('.day-content');
+    days.forEach(dayElement => {
+        const dayId = dayElement.id;
+        const dayNum = parseInt(dayId.replace('day', ''));
+        const dayTitle = dayElement.querySelector('h2')?.textContent || `Day ${dayNum}`;
+
+        // Index all headings and paragraphs
+        const elements = dayElement.querySelectorAll('h2, h3, h4, p, li, td, th, code');
+        elements.forEach((element, index) => {
+            const text = element.textContent.trim();
+            if (text.length > 0) {
+                searchIndex.push({
+                    dayNum,
+                    dayId,
+                    dayTitle,
+                    text,
+                    element,
+                    tagName: element.tagName.toLowerCase(),
+                    // Get section context (nearest heading)
+                    section: getParentHeading(element)
+                });
+            }
+        });
+    });
+}
+
+/**
+ * Get the nearest parent heading for context
+ * @param {HTMLElement} element - The element to find context for
+ * @returns {string} The heading text or empty string
+ */
+function getParentHeading(element) {
+    let current = element;
+    while (current && current.tagName !== 'BODY') {
+        if (/^H[2-4]$/.test(current.tagName)) {
+            return current.textContent.trim();
+        }
+        current = current.previousElementSibling || current.parentElement;
+    }
+    return '';
+}
+
+/**
+ * Handle search input
+ * @param {Event} e - Input event
+ */
+function handleSearch(e) {
+    const query = e.target.value.trim();
+    const resultsContainer = document.getElementById('search-results');
+    const searchClear = document.getElementById('search-clear');
+
+    // Show/hide clear button
+    if (searchClear) {
+        searchClear.style.display = query ? 'block' : 'none';
+    }
+
+    // Clear previous results
+    clearHighlights();
+    currentResults = [];
+    currentResultIndex = -1;
+
+    if (query.length < 2) {
+        if (resultsContainer) {
+            resultsContainer.style.display = 'none';
+            resultsContainer.innerHTML = '';
+        }
+        return;
+    }
+
+    // Perform search
+    const results = performSearch(query);
+    currentResults = results;
+
+    // Display results
+    displaySearchResults(results, query);
+}
+
+/**
+ * Perform search against the index
+ * @param {string} query - Search query
+ * @returns {Array} Array of search results
+ */
+function performSearch(query) {
+    const lowerQuery = query.toLowerCase();
+    const results = [];
+    const seenSections = new Set();
+
+    searchIndex.forEach(entry => {
+        const lowerText = entry.text.toLowerCase();
+        if (lowerText.includes(lowerQuery)) {
+            // Create unique key for deduplication
+            const key = `${entry.dayNum}-${entry.section}`;
+
+            // Limit results per section to avoid overwhelming UI
+            if (!seenSections.has(key) || seenSections.size < 50) {
+                results.push({
+                    ...entry,
+                    // Calculate relevance score
+                    score: calculateRelevance(entry.text, query, entry.tagName)
+                });
+                seenSections.add(key);
+            }
+        }
+    });
+
+    // Sort by relevance (score) and day number
+    results.sort((a, b) => {
+        if (b.score !== a.score) return b.score - a.score;
+        return a.dayNum - b.dayNum;
+    });
+
+    return results.slice(0, 30); // Limit to top 30 results
+}
+
+/**
+ * Calculate relevance score for search results
+ * @param {string} text - Text to score
+ * @param {string} query - Search query
+ * @param {string} tagName - HTML tag name
+ * @returns {number} Relevance score
+ */
+function calculateRelevance(text, query, tagName) {
+    const lowerText = text.toLowerCase();
+    const lowerQuery = query.toLowerCase();
+    let score = 0;
+
+    // Exact match gets highest score
+    if (lowerText === lowerQuery) score += 100;
+
+    // Match at start of text
+    if (lowerText.startsWith(lowerQuery)) score += 50;
+
+    // Match in headings is more relevant
+    if (tagName === 'h2') score += 30;
+    else if (tagName === 'h3') score += 20;
+    else if (tagName === 'h4') score += 10;
+
+    // Word boundary match
+    if (new RegExp(`\\b${escapeRegex(lowerQuery)}\\b`).test(lowerText)) {
+        score += 25;
+    }
+
+    // Case-sensitive exact match bonus
+    if (text.includes(query)) score += 15;
+
+    // Shorter text with match is more relevant
+    if (text.length < 100) score += 5;
+
+    return score;
+}
+
+/**
+ * Display search results in the sidebar
+ * @param {Array} results - Search results to display
+ * @param {string} query - Original search query
+ */
+function displaySearchResults(results, query) {
+    const resultsContainer = document.getElementById('search-results');
+    if (!resultsContainer) return;
+
+    if (results.length === 0) {
+        resultsContainer.style.display = 'block';
+        resultsContainer.innerHTML = `
+            <div class="search-no-results">
+                No results found for "${escapeHtml(query)}"
+            </div>
+        `;
+        return;
+    }
+
+    resultsContainer.style.display = 'block';
+    resultsContainer.innerHTML = `
+        <div class="search-results-header">
+            <strong>${results.length}</strong> result${results.length === 1 ? '' : 's'} found
+        </div>
+        ${results.map((result, index) => `
+            <div class="search-result-item" onclick="navigateToResult(${index})" data-index="${index}">
+                <div class="search-result-day">Day ${result.dayNum}</div>
+                <div class="search-result-section">${escapeHtml(result.section || result.dayTitle)}</div>
+                <div class="search-result-preview">${highlightText(result.text, query, 100)}</div>
+            </div>
+        `).join('')}
+    `;
+}
+
+/**
+ * Navigate to a specific search result
+ * @param {number} index - Index of result to navigate to
+ */
+function navigateToResult(index) {
+    if (index < 0 || index >= currentResults.length) return;
+
+    const result = currentResults[index];
+    currentResultIndex = index;
+
+    // Switch to the day containing the result
+    showDay(result.dayNum);
+
+    // Scroll to and highlight the element
+    setTimeout(() => {
+        clearHighlights();
+        highlightElement(result.element);
+        result.element.scrollIntoView({ behavior: 'smooth', block: 'center' });
+
+        // Update active result in sidebar
+        document.querySelectorAll('.search-result-item').forEach((item, i) => {
+            item.classList.toggle('active', i === index);
+        });
+    }, 100);
+}
+
+/**
+ * Navigate to next search result (called on Enter key)
+ */
+function navigateToNextResult() {
+    if (currentResults.length === 0) return;
+
+    currentResultIndex = (currentResultIndex + 1) % currentResults.length;
+    navigateToResult(currentResultIndex);
+}
+
+/**
+ * Highlight a specific element in the content
+ * @param {HTMLElement} element - Element to highlight
+ */
+function highlightElement(element) {
+    element.classList.add('search-highlight');
+
+    // Remove highlight after 3 seconds
+    setTimeout(() => {
+        element.classList.remove('search-highlight');
+    }, 3000);
+}
+
+/**
+ * Clear all search highlights
+ */
+function clearHighlights() {
+    document.querySelectorAll('.search-highlight').forEach(el => {
+        el.classList.remove('search-highlight');
+    });
+}
+
+/**
+ * Clear search input and results
+ */
+function clearSearch() {
+    const searchInput = document.getElementById('search-input');
+    const resultsContainer = document.getElementById('search-results');
+    const searchClear = document.getElementById('search-clear');
+
+    if (searchInput) {
+        searchInput.value = '';
+        searchInput.focus();
+    }
+
+    if (resultsContainer) {
+        resultsContainer.style.display = 'none';
+        resultsContainer.innerHTML = '';
+    }
+
+    if (searchClear) {
+        searchClear.style.display = 'none';
+    }
+
+    clearHighlights();
+    currentResults = [];
+    currentResultIndex = -1;
+}
+
+/**
+ * Highlight query text within a longer string
+ * @param {string} text - Text to highlight within
+ * @param {string} query - Query to highlight
+ * @param {number} maxLength - Maximum length of preview
+ * @returns {string} HTML with highlighted text
+ */
+function highlightText(text, query, maxLength = 100) {
+    const lowerText = text.toLowerCase();
+    const lowerQuery = query.toLowerCase();
+    const index = lowerText.indexOf(lowerQuery);
+
+    if (index === -1) {
+        return escapeHtml(text.substring(0, maxLength)) + (text.length > maxLength ? '...' : '');
+    }
+
+    // Get context around the match
+    const start = Math.max(0, index - 30);
+    const end = Math.min(text.length, index + query.length + 70);
+
+    let preview = text.substring(start, end);
+    if (start > 0) preview = '...' + preview;
+    if (end < text.length) preview = preview + '...';
+
+    // Highlight the query
+    const regex = new RegExp(`(${escapeRegex(query)})`, 'gi');
+    preview = escapeHtml(preview).replace(
+        new RegExp(`(${escapeRegex(escapeHtml(query))})`, 'gi'),
+        '<mark>$1</mark>'
+    );
+
+    return preview;
+}
+
+/**
+ * Escape HTML special characters
+ * @param {string} text - Text to escape
+ * @returns {string} Escaped text
+ */
+function escapeHtml(text) {
+    const div = document.createElement('div');
+    div.textContent = text;
+    return div.innerHTML;
+}
+
+/**
+ * Escape regex special characters
+ * @param {string} str - String to escape
+ * @returns {string} Escaped string
+ */
+function escapeRegex(str) {
+    return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
+}
+
+/**
+ * Debounce function to limit execution rate
+ * @param {Function} func - Function to debounce
+ * @param {number} wait - Wait time in milliseconds
+ * @returns {Function} Debounced function
+ */
+function debounce(func, wait) {
+    let timeout;
+    return function executedFunction(...args) {
+        const later = () => {
+            clearTimeout(timeout);
+            func.apply(this, args);
+        };
+        clearTimeout(timeout);
+        timeout = setTimeout(later, wait);
+    };
+}
diff --git a/src/styles/components.css b/src/styles/components.css
index 2460475..bb1f7f2 100644
--- a/src/styles/components.css
+++ b/src/styles/components.css
@@ -47,6 +47,212 @@
     color: var(--warning);
 }
 
+/* ----------------------------------------
+   Search Component
+   ---------------------------------------- */
+.search-container {
+    margin-bottom: 20px;
+}
+
+.search-input-wrapper {
+    position: relative;
+    display: flex;
+    align-items: center;
+}
+
+.search-icon {
+    position: absolute;
+    left: 14px;
+    color: var(--text-secondary);
+    pointer-events: none;
+}
+
+.search-input {
+    width: 100%;
+    padding: 12px 40px 12px 40px;
+    border: 2px solid var(--border);
+    border-radius: 10px;
+    background-color: var(--bg-primary);
+    color: var(--text-primary);
+    font-size: 14px;
+    font-family: inherit;
+    transition: all 0.2s;
+}
+
+.search-input:focus {
+    outline: none;
+    border-color: var(--accent);
+    background-color: var(--bg-secondary);
+}
+
+.search-input::placeholder {
+    color: var(--text-secondary);
+}
+
+.search-clear {
+    position: absolute;
+    right: 10px;
+    background: none;
+    border: none;
+    color: var(--text-secondary);
+    cursor: pointer;
+    padding: 4px;
+    border-radius: 4px;
+    transition: all 0.2s;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+}
+
+.search-clear:hover {
+    background-color: var(--bg-tertiary);
+    color: var(--text-primary);
+}
+
+/* Search Results */
+.search-results {
+    margin-top: 12px;
+    max-height: 400px;
+    overflow-y: auto;
+    background-color: var(--bg-primary);
+    border: 1px solid var(--border);
+    border-radius: 10px;
+    padding: 10px;
+}
+
+.search-results-header {
+    padding: 10px 12px;
+    font-size: 13px;
+    color: var(--text-secondary);
+    border-bottom: 1px solid var(--border);
+    margin-bottom: 8px;
+}
+
+.search-results-header strong {
+    color: var(--accent);
+    font-weight: 600;
+}
+
+.search-result-item {
+    padding: 12px;
+    margin-bottom: 6px;
+    background-color: var(--bg-secondary);
+    border-radius: 8px;
+    cursor: pointer;
+    transition: all 0.2s;
+    border-left: 3px solid transparent;
+}
+
+.search-result-item:hover {
+    background-color: var(--accent-light);
+    border-left-color: var(--accent);
+    transform: translateX(2px);
+}
+
+.search-result-item.active {
+    background-color: var(--accent);
+    color: white;
+    border-left-color: var(--warning);
+}
+
+.search-result-day {
+    font-size: 11px;
+    font-weight: 700;
+    color: var(--accent);
+    text-transform: uppercase;
+    margin-bottom: 4px;
+}
+
+.search-result-item.active .search-result-day {
+    color: var(--warning);
+}
+
+.search-result-section {
+    font-size: 13px;
+    font-weight: 600;
+    margin-bottom: 6px;
+    color: var(--text-primary);
+}
+
+.search-result-item.active .search-result-section {
+    color: white;
+}
+
+.search-result-preview {
+    font-size: 12px;
+    color: var(--text-secondary);
+    line-height: 1.4;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    display: -webkit-box;
+    -webkit-line-clamp: 2;
+    -webkit-box-orient: vertical;
+}
+
+.search-result-item.active .search-result-preview {
+    color: rgba(255, 255, 255, 0.9);
+}
+
+.search-result-preview mark {
+    background-color: var(--warning);
+    color: var(--text-primary);
+    padding: 2px 4px;
+    border-radius: 3px;
+    font-weight: 600;
+}
+
+.search-result-item.active .search-result-preview mark {
+    background-color: white;
+    color: var(--accent);
+}
+
+.search-no-results {
+    padding: 20px;
+    text-align: center;
+    color: var(--text-secondary);
+    font-size: 14px;
+}
+
+/* Search Highlight in Content */
+.search-highlight {
+    background-color: var(--warning);
+    padding: 4px 6px;
+    border-radius: 4px;
+    animation: highlight-pulse 0.5s ease-in-out;
+    box-shadow: 0 0 0 4px var(--warning-light);
+}
+
+@keyframes highlight-pulse {
+    0% {
+        box-shadow: 0 0 0 0 var(--warning-light);
+    }
+    50% {
+        box-shadow: 0 0 0 8px var(--warning-light);
+    }
+    100% {
+        box-shadow: 0 0 0 4px var(--warning-light);
+    }
+}
+
+/* Scrollbar for search results */
+.search-results::-webkit-scrollbar {
+    width: 6px;
+}
+
+.search-results::-webkit-scrollbar-track {
+    background: var(--bg-secondary);
+    border-radius: 10px;
+}
+
+.search-results::-webkit-scrollbar-thumb {
+    background: var(--accent);
+    border-radius: 10px;
+}
+
+.search-results::-webkit-scrollbar-thumb:hover {
+    background: var(--accent-hover);
+}
+
 /* ----------------------------------------
    Buttons
    ---------------------------------------- */