Activate when:

Implementing meta tags (title, description, keywords)
Adding Open Graph or Twitter card tags
Creating structured data (JSON-LD, schema.org)
Generating sitemaps or robots.txt
Optimizing for search engines
Improving social media sharing
Adding canonical URLs
Implementing semantic HTML
Optimizing Core Web Vitals
Ensuring mobile-friendliness
Improving accessibility for SEO

Core SEO Elements

1. Essential Meta Tags

Basic Meta Tags:

<head>
  <!-- Primary Meta Tags -->
  <title>Page Title | Site Name</title>
  <meta name="title" content="Page Title | Site Name" />
  <meta name="description" content="Clear, concise description (150-160 chars)" />
  <meta name="keywords" content="keyword1, keyword2, keyword3" />

  <!-- Viewport for Mobile -->
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />

  <!-- Canonical URL -->
  <link rel="canonical" href="https://example.com/page" />

  <!-- Language -->
  <html lang="en">
</head>

Best Practices:

✅ Title: 50-60 characters, include primary keyword
✅ Description: 150-160 characters, compelling, includes CTA
✅ Unique per page
✅ Include brand name in title
✅ Keywords: 5-10 relevant terms (deprecated but some engines still use)

2. Open Graph Tags (Social Media)

Facebook/LinkedIn/Most Platforms:

<!-- Open Graph / Facebook -->
<meta property="og:type" content="website" />
<meta property="og:url" content="https://example.com/page" />
<meta property="og:title" content="Page Title" />
<meta property="og:description" content="Description for social sharing" />
<meta property="og:image" content="https://example.com/image.jpg" />
<meta property="og:image:width" content="1200" />
<meta property="og:image:height" content="630" />
<meta property="og:site_name" content="Site Name" />
<meta property="og:locale" content="en_US" />

Image Requirements:

Recommended: 1200x630px (1.91:1 ratio)
Minimum: 600x315px
Format: JPG or PNG
Max file size: 8MB
Include text overlay for context

3. Twitter Card Tags

<!-- Twitter -->
<meta name="twitter:card" content="summary_large_image" />
<meta name="twitter:url" content="https://example.com/page" />
<meta name="twitter:title" content="Page Title" />
<meta name="twitter:description" content="Description for Twitter" />
<meta name="twitter:image" content="https://example.com/image.jpg" />
<meta name="twitter:site" content="@username" />
<meta name="twitter:creator" content="@username" />

Card Types:

summary: Small image (120x120px)
summary_large_image: Large image (2:1 ratio, 300x157px min)
app: Mobile app
player: Video/audio

4. Structured Data (JSON-LD)

Website/Organization:

<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "Organization",
  "name": "Company Name",
  "url": "https://example.com",
  "logo": "https://example.com/logo.png",
  "sameAs": [
    "https://twitter.com/username",
    "https://linkedin.com/company/name"
  ]
}
</script>

Article/Blog Post:

<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "Article",
  "headline": "Article Title",
  "description": "Article description",
  "image": "https://example.com/article-image.jpg",
  "datePublished": "2025-01-15T08:00:00+00:00",
  "dateModified": "2025-01-16T09:00:00+00:00",
  "author": {
    "@type": "Person",
    "name": "Author Name",
    "url": "https://example.com/author/name"
  },
  "publisher": {
    "@type": "Organization",
    "name": "Publisher Name",
    "logo": {
      "@type": "ImageObject",
      "url": "https://example.com/logo.png"
    }
  }
}
</script>

Breadcrumb:

<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": "Category",
      "item": "https://example.com/category"
    },
    {
      "@type": "ListItem",
      "position": 3,
      "name": "Page",
      "item": "https://example.com/category/page"
    }
  ]
}
</script>

Product (E-commerce):

<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "Product Name",
  "image": "https://example.com/product.jpg",
  "description": "Product description",
  "brand": {
    "@type": "Brand",
    "name": "Brand Name"
  },
  "offers": {
    "@type": "Offer",
    "url": "https://example.com/product",
    "priceCurrency": "USD",
    "price": "99.99",
    "availability": "https://schema.org/InStock"
  }
}
</script>

More Schema Types:

WebPage - Generic web page
FAQPage - FAQ pages
HowTo - Step-by-step guides
Recipe - Recipes
Event - Events
LocalBusiness - Local businesses
Review - Reviews/ratings

5. Technical SEO

Robots Meta Tag:

<!-- Allow indexing (default) -->
<meta name="robots" content="index, follow" />

<!-- Prevent indexing -->
<meta name="robots" content="noindex, nofollow" />

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

Robots.txt:

# Allow all bots
User-agent: *
Allow: /

# Disallow specific paths
Disallow: /admin/
Disallow: /private/
Disallow: /api/

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

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>2025-01-15</lastmod>
    <changefreq>daily</changefreq>
    <priority>1.0</priority>
  </url>
  <url>
    <loc>https://example.com/page</loc>
    <lastmod>2025-01-14</lastmod>
    <changefreq>weekly</changefreq>
    <priority>0.8</priority>
  </url>
</urlset>

Priority Guidelines:

Homepage: 1.0
Main category pages: 0.8
Sub-pages: 0.6
Blog posts: 0.5
Archive pages: 0.4

Canonical URLs:

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

<!-- When paginated -->
<link rel="prev" href="https://example.com/page?p=1" />
<link rel="next" href="https://example.com/page?p=3" />

6. Performance & Core Web Vitals

Key Metrics:

LCP (Largest Contentful Paint): < 2.5s
FID (First Input Delay): < 100ms
CLS (Cumulative Layout Shift): < 0.1

Optimization Techniques:

<!-- Preload critical resources -->
<link rel="preload" href="/fonts/main.woff2" as="font" type="font/woff2" crossorigin />
<link rel="preload" href="/images/hero.jpg" as="image" />

<!-- Preconnect to external domains -->
<link rel="preconnect" href="https://fonts.googleapis.com" />
<link rel="dns-prefetch" href="https://analytics.example.com" />

<!-- Lazy load images -->
<img src="image.jpg" alt="Description" loading="lazy" />

<!-- Responsive images -->
<img
  src="image-800.jpg"
  srcset="image-400.jpg 400w, image-800.jpg 800w, image-1200.jpg 1200w"
  sizes="(max-width: 600px) 400px, (max-width: 900px) 800px, 1200px"
  alt="Description"
/>

7. Semantic HTML & Accessibility

Proper HTML Structure:

<header>
  <nav aria-label="Main navigation">
    <ul>
      <li><a href="/">Home</a></li>
    </ul>
  </nav>
</header>

<main>
  <article>
    <h1>Main Heading (only one per page)</h1>
    <h2>Section Heading</h2>
    <h3>Subsection Heading</h3>

    <p>Content...</p>

    <figure>
      <img src="image.jpg" alt="Descriptive alt text" />
      <figcaption>Image caption</figcaption>
    </figure>
  </article>
</main>

<aside>
  <section>
    <h2>Related Content</h2>
  </section>
</aside>

<footer>
  <p>&copy; 2025 Company Name</p>
</footer>

Heading Hierarchy:

✅ One <h1> per page (usually page title)
✅ Don't skip levels (h1 → h2 → h3, not h1 → h3)
✅ Use headings for structure, not styling
✅ Screen readers use headings for navigation

Alt Text Best Practices:

<!-- Descriptive alt text -->
<img src="sunset.jpg" alt="Golden sunset over mountain range" />

<!-- Decorative images -->
<img src="decoration.svg" alt="" role="presentation" />

<!-- Complex images -->
<figure>
  <img src="chart.png" alt="Sales chart showing 25% growth" />
  <figcaption>
    Detailed description: Sales increased from $100k to $125k in Q4...
  </figcaption>
</figure>

8. Mobile Optimization

Viewport Configuration:

<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta name="theme-color" content="#0066cc" />
<meta name="mobile-web-app-capable" content="yes" />

Responsive Design Checklist:

✅ Mobile-first approach
✅ Touch targets ≥ 48x48px
✅ Readable font sizes (16px minimum)
✅ No horizontal scrolling
✅ Fast load times on 3G
✅ Test on real devices

9. Additional SEO Elements

Favicons & App Icons:

<link rel="icon" type="image/png" sizes="32x32" href="/favicon-32x32.png" />
<link rel="icon" type="image/png" sizes="16x16" href="/favicon-16x16.png" />
<link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png" />
<link rel="manifest" href="/site.webmanifest" />

Web App Manifest (site.webmanifest):

{
  "name": "App Name",
  "short_name": "App",
  "icons": [
    {
      "src": "/android-chrome-192x192.png",
      "sizes": "192x192",
      "type": "image/png"
    },
    {
      "src": "/android-chrome-512x512.png",
      "sizes": "512x512",
      "type": "image/png"
    }
  ],
  "theme_color": "#ffffff",
  "background_color": "#ffffff",
  "display": "standalone"
}

Language & Internationalization:

<html lang="en">
<head>
  <!-- Alternate language versions -->
  <link rel="alternate" hreflang="en" href="https://example.com/en/page" />
  <link rel="alternate" hreflang="es" href="https://example.com/es/page" />
  <link rel="alternate" hreflang="x-default" href="https://example.com/page" />
</head>

Implementation Patterns

React/Next.js Example

import Head from 'next/head';

interface SEOProps {
  title: string;
  description: string;
  canonical?: string;
  ogImage?: string;
  ogType?: 'website' | 'article';
  publishedTime?: string;
  modifiedTime?: string;
}

export function SEO({
  title,
  description,
  canonical,
  ogImage = '/default-og-image.jpg',
  ogType = 'website',
  publishedTime,
  modifiedTime,
}: SEOProps) {
  const fullTitle = `${title} | Site Name`;
  const url = canonical || `https://example.com`;
  const fullOgImage = ogImage.startsWith('http')
    ? ogImage
    : `https://example.com${ogImage}`;

  return (
    <Head>
      <title>{fullTitle}</title>
      <meta name="description" content={description} />
      <link rel="canonical" href={url} />

      {/* Open Graph */}
      <meta property="og:type" content={ogType} />
      <meta property="og:url" content={url} />
      <meta property="og:title" content={fullTitle} />
      <meta property="og:description" content={description} />
      <meta property="og:image" content={fullOgImage} />

      {/* Twitter */}
      <meta name="twitter:card" content="summary_large_image" />
      <meta name="twitter:title" content={fullTitle} />
      <meta name="twitter:description" content={description} />
      <meta name="twitter:image" content={fullOgImage} />

      {/* Article specific */}
      {ogType === 'article' && publishedTime && (
        <meta property="article:published_time" content={publishedTime} />
      )}
      {ogType === 'article' && modifiedTime && (
        <meta property="article:modified_time" content={modifiedTime} />
      )}
    </Head>
  );
}

Dynamic Sitemap Generation (Next.js)

// pages/sitemap.xml.ts
import { GetServerSideProps } from 'next';

export const getServerSideProps: GetServerSideProps = async ({ res }) => {
  const baseUrl = 'https://example.com';

  // Fetch your pages/posts
  const pages = await fetchAllPages();

  const sitemap = `<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  ${pages.map(page => `
  <url>
    <loc>${baseUrl}${page.url}</loc>
    <lastmod>${page.updatedAt}</lastmod>
    <changefreq>${page.changeFreq}</changefreq>
    <priority>${page.priority}</priority>
  </url>
  `).join('')}
</urlset>`;

  res.setHeader('Content-Type', 'text/xml');
  res.write(sitemap);
  res.end();

  return { props: {} };
};

export default function Sitemap() {
  return null;
}

Testing & Validation

Tools

Google Tools:

Social Media Validators:

Schema Validation:

SEO Checklist

On-Page SEO:

Technical SEO:

Content SEO:

Unique, high-quality content
Target keyword in title, H1, first paragraph
Related keywords throughout
Content length > 300 words
Regular content updates
External links to authoritative sources

Common Pitfalls

❌ Duplicate content: Use canonical tags ❌ Missing alt text: Screen readers and SEO need it ❌ Keyword stuffing: Write naturally for humans ❌ Slow page speed: Optimize images, use CDN ❌ Not mobile-friendly: Test on devices ❌ Broken links: Check regularly ❌ Missing structured data: Implement JSON-LD ❌ Poor URL structure: Use clean, descriptive URLs ❌ No sitemap: Generate and submit ❌ Ignoring Core Web Vitals: Monitor and optimize

Status: Production-ready ✅ Line Count: < 500 ✅ Best Practices: Following Anthropic guidelines ✅

seo-specialist

SEO Specialist

Purpose

When to Use