What is SEO?
Search engine optimization is the work of making pages easy for search engines to find, understand and rank. It covers three layers: technical health (can crawlers reach and render the page?), relevance (does the content match what the searcher wants?) and authority (do other sites vouch for it through links and mentions?).
SEO is also the foundation of AI search. Google AI Overviews and AI Mode draw from Google's index, and ChatGPT search and Copilot lean on Bing's. A page that can't be crawled or ranked is rarely cited.
Why SEO matters
Organic search compounds. A page that ranks keeps earning visits without paying per click, and the same signals that help it rank, like clear structure, fast pages and trusted sources, are what AI engines look for when choosing what to quote.
How SEO works
- 01
Crawl
Search engine bots discover URLs through links and sitemaps, then fetch them, following the rules in robots.txt.
- 02
Render and index
The engine renders the page, extracts text, links and structured data, and decides whether to store it. Duplicate URLs are folded into one canonical version.
- 03
Rank
For each query, ranking systems weigh relevance, quality, usefulness, page experience and authority to order the results.
- 04
Serve
Results appear as links, rich results, featured snippets or AI-generated summaries, depending on the query.
SEO best practices
- Submit an XML sitemap and keep it free of redirects, errors and noindex pages.
- Give every page a unique title and meta description that match search intent.
- Use one H1 and a logical H2/H3 outline.
- Link related pages to each other with descriptive anchor text.
- Make pages fast and mobile-friendly, and render important content on the server.
- Earn links and mentions from relevant, reputable sites.
Common SEO mistakes
- Blocking CSS or JavaScript in robots.txt, so search engines can't render the page.
- Letting several URLs (tracking parameters, www and non-www, trailing slashes) compete without canonical tags.
- Publishing thin pages that target a keyword but don't answer the query.
- Leaving important pages orphaned, with no internal links pointing to them.
How to measure SEO
Metrics to track
- Indexed pages compared with submitted pages (Google Search Console)
- Impressions, clicks and average position by query
- Organic sessions and conversions
- Core Web Vitals pass rate
What it improves
- Crawlability and indexation
- Title, meta and heading structure
- Internal linking
- Page speed and mobile usability
SEO vs. related optimizations
These overlap with SEO. Work on one usually helps the others.
SEO FAQ
How long does SEO take to work?+
Technical fixes can show up within days of a recrawl. New content and authority usually take three to six months to rank competitively, and longer in crowded markets.
Is SEO still worth it now that AI answers questions directly?+
Yes. AI Overviews and ChatGPT search pull from search indexes, and pages that rank well are cited more often. SEO is the entry ticket to AI visibility.
Do I need a sitemap?+
Small, well-linked sites can be crawled without one, but a sitemap helps search engines find new and deep pages faster and shows indexing problems in Search Console.
What's the difference between on-page and technical SEO?+
On-page SEO is the content and HTML of a page: titles, headings, copy and internal links. Technical SEO is the infrastructure that lets search engines crawl, render and index it: status codes, sitemaps, canonicals, speed and rendering.