How Search Engines Work

Before you can optimize for search engines, you need to understand what they do. Search engines have three jobs: discover pages, understand them, and rank them.

The Three Stages

1. Crawling    → Discover pages by following links
2. Indexing    → Read and store page content
3. Ranking     → Decide which pages answer a query

Crawling

Google uses automated programs called crawlers (or Googlebot) that follow links from page to page across the web.

When Googlebot visits your site, it:

1. Fetches your page's HTML
2. Finds all the links on that page
3. Adds those links to a queue
4. Visits the next URL in the queue
5. Repeats billions of times per day

Crawl budget is how many pages Google will crawl on your site in a given timeframe. For most small-to-medium sites, crawl budget isn't a concern. But for large sites (100k+ pages), you need to make sure Google spends its budget on your important pages.

Things that waste crawl budget:

Indexing

After crawling, Google processes the page:

1. Renders the page — executes JavaScript to see the final HTML
2. Extracts content — reads text, headings, images, links
3. Understands meaning — determines what the page is about
4. Stores it — adds the page to Google's index (a massive database)

Not every crawled page gets indexed. Google may skip pages that are:

• Too similar to other pages (duplicate content)
• Too thin (very little useful content)
• Blocked by noindex tags
• Low quality or spammy

Ranking

When someone searches, Google:

1. Finds all indexed pages that match the query
2. Scores each page on hundreds of ranking factors
3. Returns results in order of relevance and quality

The main ranking factors:

How Google Finds Your Pages

Google discovers pages through:

1. Links from other sites — the primary discovery method
2. Your sitemap — an XML file listing all your pages
3. Google Search Console — you can manually submit URLs
4. Internal links — links between pages on your own site

Sitemaps

A sitemap tells Google about all the pages on your site:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
    <loc>https://example.com/</loc>
    <lastmod>2026-03-20</lastmod>
    <priority>1.0</priority>
  </url>
  <url>
    <loc>https://example.com/blog/my-post</loc>
    <lastmod>2026-03-18</lastmod>
    <priority>0.7</priority>
  </url>
</urlset>

Submit your sitemap in Google Search Console at Sitemaps > Add a new sitemap.

robots.txt

The robots.txt file tells crawlers which pages they can and cannot access:

User-agent: *
Allow: /
Disallow: /admin/
Disallow: /api/

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

• Allow — pages crawlers can visit
• Disallow — pages crawlers should skip
• This is a suggestion, not enforcement — well-behaved bots follow it, malicious ones ignore it

Google Search Console

Google Search Console (GSC) is your direct line to Google. It shows you:

• Which pages are indexed (and which aren't)
• What queries bring traffic to your site
• Crawl errors and issues
• Mobile usability problems
• Core Web Vitals scores

Every website owner should set up GSC. It's free and essential for understanding how Google sees your site.

Key Reports

Summary

• Search engines crawl (discover), index (understand), and rank (order) pages
• Googlebot follows links to discover new pages — internal linking matters
• Not every crawled page gets indexed — content quality and uniqueness matter
• Ranking depends on relevance, quality, authority, and user experience
• Use Google Search Console to monitor how Google sees your site
• Submit a sitemap to help Google find all your pages