What is technical SEO?

How Google gets a page into its results

Google Search works in three stages. Crawling is when Google downloads text, images and videos from pages it has found. Indexing is when Google analyses that content and stores it. Serving is when Google returns the pages it judges relevant to a search.

Google finds most pages through links from pages it has already crawled. A sitemap, a file listing the URLs you want indexed, is optional. Google also says plainly that it does not guarantee it will crawl, index or serve any page, even when a site follows its guidelines. Technical SEO is about removing anything that stops a page getting through these stages.

The three minimum requirements

Google's Search Essentials list three technical requirements for a page to be eligible for indexing:

1. Googlebot is not blocked. Pages behind a login, or blocked by robots.txt, will not be crawled.
2. The page works, meaning Google receives an HTTP 200 (success) status code. Pages returning client or server errors are not indexed.
3. The page has indexable content, in a file type Google supports, that does not break Google's spam policies.

A common mistake is using robots.txt to hide a page. Google says robots.txt is used mainly to manage crawler traffic and is not a mechanism for keeping a page out of Google. To keep a page out of results, use noindex or password protection.

Duplicates, rendering and mobile

• Duplicate URLs: the same content at several addresses is not a spam problem, but it wastes crawling. Google prefers a 301 redirect to your chosen URL, or a rel="canonical" link element where a redirect is not possible.
• Rendering: Googlebot renders pages with a recent version of Chrome and runs JavaScript. Do not block the CSS or JavaScript files your pages need, or Google may not understand them.
• Mobile: Google uses the mobile version of a page, crawled with its smartphone agent, for indexing and ranking. Your mobile pages need the same main content, structured data, title and meta description as desktop.
• URLs: descriptive URLs are more useful to people than random identifiers, and grouping similar pages into folders helps Google understand larger sites.

Page experience and Core Web Vitals

Core Web Vitals are Google's measures of loading, responsiveness and visual stability. The targets are:

• Largest Contentful Paint (LCP) within 2.5 seconds.
• Interaction to Next Paint (INP) under 200 milliseconds.
• Cumulative Layout Shift (CLS) under 0.1.

Google recommends reaching good Core Web Vitals, but it also says there is no single page experience signal, and that its systems will still show the most relevant content even when page experience is weaker. Speed helps most when many helpful pages are competing for the same search.

A quick technical check you can do today

1. Search Google for site:yourdomain.com. If nothing appears, start with the three requirements above.
2. In Search Console, open the Page indexing report to see which URLs are not indexed and why.
3. Paste an important URL into the URL Inspection bar at the top of Search Console, then click Test live URL to see what Google can fetch and render.
4. Open the Core Web Vitals report in Search Console to see how your pages perform.
5. Check the HTTPS report to find any pages not served securely.

After a fix, give it time. Google's starter guide says changes can take from a few hours to several months to show, and suggests waiting a few weeks before judging the result.

Sources

• Google Search Central: In-depth guide to how Google Search works (crawling, indexing, serving, rendering)
• Google Search Central: SEO Starter Guide (discovery, sitemaps, site: search, duplicates, URLs, timing)
• Google Search Essentials: Technical requirements
• Google Search Central: Introduction to robots.txt
• Google Search Central: Mobile-first indexing best practices
• Google Search Central: Core Web Vitals and Search (thresholds)
• Google Search Central: Page experience (no single signal, relevance)

Frequently asked questions

Is technical SEO more important than content?

They do different jobs. Technical work makes a page eligible to appear, because a page Google cannot crawl or index cannot rank at all. Once a page is eligible, Google says its systems always try to show the most relevant content, even when page experience is not perfect. Good technical foundations help helpful content compete. They do not replace it.

Do I need a sitemap for technical SEO?

Not always. Google's SEO Starter Guide says most pages are found through links from pages Google has already crawled, and that a sitemap is optional. A sitemap is still useful for new sites, large sites and site moves, because it lists the URLs you want Google to know about. Many content management systems generate one for you automatically.