Term
Technical SEO
The part of optimisation that makes sure search engines can crawl, render and index a site: speed, mobile version, robots.txt, sitemap, canonical URLs, redirects and structured data. Without it even the best content will not help.
Updated
What it means
Technical SEO is the part of search engine optimisation that makes sure search engines can crawl, render and index a website. It is not about the text itself but about the technical foundations without which even the best content has no chance of appearing in search results.
It covers loading speed and Core Web Vitals, the mobile version, the robots.txt file, the XML sitemap, canonical URLs, redirects, HTTPS, language versions and structured data that describe a page's content to search engines.
Technical SEO is a prerequisite for the other parts of optimisation, namely on-page content work and link building. If a search engine cannot load a page or treats it as a duplicate of another, its content and the links pointing to it do not have the intended effect.
How it works in practice
When launching a new site or redesigning one, setting up 301 redirects from old addresses to new ones is crucial. Without them the history, links and rankings built over years are lost, and visitors land on error pages.
Regular checks in search engine tools reveal indexing errors, broken links, mobile issues or slow pages. For larger sites, such as glossaries with thousands of terms, it also matters to make efficient use of the crawl capacity the search engine allocates to the site.
Structured data, for example for the organisation, articles, FAQs or term definitions, helps search engines and AI services understand the content better. It can lead to rich results in search and to the site being cited more often in assistants' answers.
What to watch out for
A single wrong tag can remove a whole site from search, for example a noindex directive left over from a staging version or misconfigured canonical URLs. After every major deployment it is therefore worth checking that important pages can be indexed.
Technical SEO is not a one-off task. CMS updates, new templates or plugins can unexpectedly change a page's output. Regular audits and automated tests at deployment help catch problems before they affect traffic.
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