SEO optimization

Search engine optimization based on Lighthouse SEO audits and Google Search guidelines. Focus on technical SEO, on-page optimization, and structured data.

SEO fundamentals

Search ranking factors (approximate influence):

Factor	Influence	This Skill
Content quality & relevance	~40%	Partial (structure)
Backlinks & authority	~25%	✗
Technical SEO	~15%	✓
Page experience (Core Web Vitals)	~10%	See Core Web Vitals
On-page SEO	~10%	✓

Technical SEO

Crawlability

robots.txt:

# /robots.txt
User-agent: *
Allow: /

# Block admin/private areas
Disallow: /admin/
Disallow: /api/
Disallow: /private/

# Don't block resources needed for rendering
# ❌ Disallow: /static/

Sitemap: https://example.com/sitemap.xml

Meta robots:

<!-- Default: indexable, followable -->
<meta name="robots" content="index, follow" />

<!-- Noindex specific pages -->
<meta name="robots" content="noindex, nofollow" />

<!-- Indexable but don't follow links -->
<meta name="robots" content="index, nofollow" />

<!-- Control snippets -->
<meta name="robots" content="max-snippet:150, max-image-preview:large" />

Canonical URLs:

<!-- Prevent duplicate content issues -->
<link rel="canonical" href="https://example.com/page" />

<!-- Self-referencing canonical (recommended) -->
<link rel="canonical" href="https://example.com/current-page" />

<!-- For paginated content -->
<link rel="canonical" href="https://example.com/products" />
<!-- Or use rel="prev" / rel="next" for explicit pagination -->

XML sitemap

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
    <loc>https://example.com/</loc>
    <lastmod>2024-01-15</lastmod>
    <changefreq>daily</changefreq>
    <priority>1.0</priority>
  </url>
  <url>
    <loc>https://example.com/products</loc>
    <lastmod>2024-01-14</lastmod>
    <changefreq>weekly</changefreq>
    <priority>0.8</priority>
  </url>
</urlset>

Sitemap best practices:

Maximum 50,000 URLs or 50MB per sitemap
Use sitemap index for larger sites
Include only canonical, indexable URLs
Update lastmod when content changes
Submit to Google Search Console

URL structure

✅ Good URLs:
https://example.com/products/blue-widget
https://example.com/blog/how-to-use-widgets

❌ Poor URLs:
https://example.com/p?id=12345
https://example.com/products/item/category/subcategory/blue-widget-2024-sale-discount

URL guidelines:

Use hyphens, not underscores
Lowercase only
Keep short (< 75 characters)
Include target keywords naturally
Avoid parameters when possible
Use HTTPS always

HTTPS & security

<!-- Ensure all resources use HTTPS -->
<img src="https://example.com/image.jpg" />

<!-- Not: -->
<img src="http://example.com/image.jpg" />

Security headers for SEO trust signals:

Strict-Transport-Security: max-age=31536000; includeSubDomains
X-Content-Type-Options: nosniff
X-Frame-Options: DENY

On-page SEO

Title tags

<!-- ❌ Missing or generic -->
<title>Page</title>
<title>Home</title>

<!-- ✅ Descriptive with primary keyword -->
<title>Blue Widgets for Sale | Premium Quality | Example Store</title>

Title tag guidelines:

50-60 characters (Google truncates ~60)
Primary keyword near the beginning
Unique for every page
Brand name at end (unless homepage)
Action-oriented when appropriate

Meta descriptions

<!-- ❌ Missing or duplicate -->
<meta name="description" content="" />

<!-- ✅ Compelling and unique -->
<meta
  name="description"
  content="Shop premium blue widgets with free shipping. 30-day returns. Rated 4.9/5 by 10,000+ customers. Order today and save 20%."
/>

Meta description guidelines:

150-160 characters
Include primary keyword naturally
Compelling call-to-action
Unique for every page
Matches page content

Heading structure

<!-- ❌ Poor structure -->
<h2>Welcome to Our Store</h2>
<h4>Products</h4>
<h1>Contact Us</h1>

<!-- ✅ Proper hierarchy -->
<h1>Blue Widgets - Premium Quality</h1>
<h2>Product Features</h2>
<h3>Durability</h3>
<h3>Design</h3>
<h2>Customer Reviews</h2>
<h2>Pricing</h2>

Heading guidelines:

Single <h1> per page (the main topic)
Logical hierarchy (don't skip levels)
Include keywords naturally
Descriptive, not generic

Image SEO

<!-- ❌ Poor image SEO -->
<img src="IMG_12345.jpg" />

<!-- ✅ Optimized image -->
<img
  src="blue-widget-product-photo.webp"
  alt="Blue widget with chrome finish, side view showing control panel"
  width="800"
  height="600"
  loading="lazy"
/>

Image guidelines:

Descriptive filenames with keywords
Alt text describes the image content
Compressed and properly sized
WebP/AVIF with fallbacks
Lazy load below-fold images

Internal linking

<!-- ❌ Non-descriptive -->
<a href="/products">Click here</a>
<a href="/widgets">Read more</a>

<!-- ✅ Descriptive anchor text -->
<a href="/products/blue-widgets">Browse our blue widget collection</a>
<a href="/guides/widget-maintenance">Learn how to maintain your widgets</a>

Linking guidelines:

Descriptive anchor text with keywords
Link to relevant internal pages
Reasonable number of links per page
Fix broken links promptly
Use breadcrumbs for hierarchy

Structured data (JSON-LD)

Organization

<script type="application/ld+json">
  {
    "@context": "https://schema.org",
    "@type": "Organization",
    "name": "Example Company",
    "url": "https://example.com",
    "logo": "https://example.com/logo.png",
    "sameAs": ["https://twitter.com/example", "https://linkedin.com/company/example"],
    "contactPoint": {
      "@type": "ContactPoint",
      "telephone": "+1-555-123-4567",
      "contactType": "customer service"
    }
  }
</script>

Article

<script type="application/ld+json">
  {
    "@context": "https://schema.org",
    "@type": "Article",
    "headline": "How to Choose the Right Widget",
    "description": "Complete guide to selecting widgets for your needs.",
    "image": "https://example.com/article-image.jpg",
    "author": {
      "@type": "Person",
      "name": "Jane Smith",
      "url": "https://example.com/authors/jane-smith"
    },
    "publisher": {
      "@type": "Organization",
      "name": "Example Blog",
      "logo": {
        "@type": "ImageObject",
        "url": "https://example.com/logo.png"
      }
    },
    "datePublished": "2024-01-15",
    "dateModified": "2024-01-20"
  }
</script>

Product

<script type="application/ld+json">
  {
    "@context": "https://schema.org",
    "@type": "Product",
    "name": "Blue Widget Pro",
    "image": "https://example.com/blue-widget.jpg",
    "description": "Premium blue widget with advanced features.",
    "brand": {
      "@type": "Brand",
      "name": "WidgetCo"
    },
    "offers": {
      "@type": "Offer",
      "price": "49.99",
      "priceCurrency": "USD",
      "availability": "https://schema.org/InStock",
      "url": "https://example.com/products/blue-widget"
    },
    "aggregateRating": {
      "@type": "AggregateRating",
      "ratingValue": "4.8",
      "reviewCount": "1250"
    }
  }
</script>

FAQ

<script type="application/ld+json">
  {
    "@context": "https://schema.org",
    "@type": "FAQPage",
    "mainEntity": [
      {
        "@type": "Question",
        "name": "What colors are available?",
        "acceptedAnswer": {
          "@type": "Answer",
          "text": "Our widgets come in blue, red, and green."
        }
      },
      {
        "@type": "Question",
        "name": "What is the warranty?",
        "acceptedAnswer": {
          "@type": "Answer",
          "text": "All widgets include a 2-year warranty."
        }
      }
    ]
  }
</script>

Breadcrumbs

<script type="application/ld+json">
  {
    "@context": "https://schema.org",
    "@type": "BreadcrumbList",
    "itemListElement": [
      {
        "@type": "ListItem",
        "position": 1,
        "name": "Home",
        "item": "https://example.com"
      },
      {
        "@type": "ListItem",
        "position": 2,
        "name": "Products",
        "item": "https://example.com/products"
      },
      {
        "@type": "ListItem",
        "position": 3,
        "name": "Blue Widgets",
        "item": "https://example.com/products/blue-widgets"
      }
    ]
  }
</script>

Validation

Test structured data at:

Mobile SEO

Responsive design

<!-- ❌ Not mobile-friendly -->
<meta name="viewport" content="width=1024" />

<!-- ✅ Responsive viewport -->
<meta name="viewport" content="width=device-width, initial-scale=1" />

Tap targets

/* ❌ Too small for mobile */
.small-link {
  padding: 4px;
  font-size: 12px;
}

/* ✅ Adequate tap target */
.mobile-friendly-link {
  padding: 12px;
  font-size: 16px;
  min-height: 48px;
  min-width: 48px;
}

Font sizes

/* ❌ Too small on mobile */
body {
  font-size: 10px;
}

/* ✅ Readable without zooming */
body {
  font-size: 16px;
  line-height: 1.5;
}

International SEO

Hreflang tags

<!-- For multi-language sites -->
<link rel="alternate" hreflang="en" href="https://example.com/page" />
<link rel="alternate" hreflang="es" href="https://example.com/es/page" />
<link rel="alternate" hreflang="fr" href="https://example.com/fr/page" />
<link rel="alternate" hreflang="x-default" href="https://example.com/page" />

Language declaration

<html lang="en">
  <!-- or -->
  <html lang="es-MX"></html>
</html>

SEO audit checklist

Critical

High priority

Medium priority

Ongoing

Fix crawl errors in Search Console
Update sitemap when content changes
Monitor ranking changes
Check for broken links
Review Search Console insights

Tools

Tool	Use
Google Search Console	Monitor indexing, fix issues
Google PageSpeed Insights	Performance + Core Web Vitals
Rich Results Test	Validate structured data
Lighthouse	Full SEO audit
Screaming Frog	Crawl analysis

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