How Search Engines Work

Before diving into Next.js-specific implementations, let's understand how search engines work. This foundational knowledge will help you make better decisions throughout your SEO journey.

The Three Stages of Search

Search engines like Google operate in three stages:

1. Crawling

Googlebot (Google's web crawler) discovers pages by following links. When it visits a page, it:

• Downloads the HTML content
• Executes JavaScript (important for React apps)
• Follows links to discover new pages
• Respects directives in robots.txt

Why this matters for Next.js: Server-rendered pages are immediately readable by crawlers. Client-only content may have indexing delays or issues.

2. Indexing

After crawling, Google processes the content and stores it in its index. During indexing, Google:

• Analyzes the page content and structure
• Extracts metadata (title, description)
• Understands the page's topic and relevance
• Stores the page for retrieval during searches

Why this matters for Next.js: Proper metadata and structured data help Google understand your content accurately.

3. Ranking

When a user searches, Google retrieves relevant pages from its index and ranks them based on hundreds of factors, including:

• Content relevance and quality
• Page experience (Core Web Vitals)
• Mobile-friendliness
• HTTPS security
• Backlinks from other sites

How Googlebot Sees Your Site

Googlebot is essentially a browser that renders your pages. Here's what it does:

1. Requests the URL - Fetches the initial HTML
2. Parses HTML - Reads the document structure
3. Discovers resources - Finds CSS, JS, images
4. Executes JavaScript - Renders the page like a browser
5. Captures the result - Stores the final rendered content

JavaScript Rendering

Google can execute JavaScript, but there are caveats:

• Rendering is deferred - JS pages go into a render queue
• Resources must be accessible - Don't block CSS/JS in robots.txt
• Timeouts exist - Very slow pages may not fully render

This is why Server Components in Next.js are SEO-friendly - content is in the initial HTML.

The Crawl Budget

Google allocates a "crawl budget" to each site - how many pages it will crawl in a given time period. Factors affecting crawl budget:

• Site size - Larger sites get more budget
• Server speed - Faster responses = more crawling
• Site health - Errors reduce crawling
• Link structure - Well-linked pages get discovered

Optimizing Crawl Budget

// Help Google find important pages
// Use internal linking strategically

// In your navigation or footer
<Link href="/courses">All Courses</Link>
<Link href="/blog">Blog</Link>

// In content, link to related pages
<p>
  Learn more in our
  <Link href="/courses/nextjs-fundamentals">Next.js Fundamentals</Link> course.
</p>

Summary

In this lesson, you learned:

• Search engines crawl, index, and rank pages
• Googlebot renders JavaScript but prefers HTML content
• Server-rendered pages are more reliably indexed
• Crawl budget determines how often your pages are visited
• Internal linking helps discovery

In the next lesson, we'll explore the key ranking factors you can control as a developer.