Great content can’t rank if search engines can’t reach it, can’t load it properly, or get confused about which version to show. Technical SEO deals with the foundations: how the site is built and served, rather than what the pages say.
It’s often invisible to visitors. A page can look perfect in a browser while telling Google not to index it.
What technical SEO covers
Crawling. Robots.txt rules, internal links that crawlers can follow, XML sitemaps, crawl budget on large sites (see crawling).
Indexing. Noindex tags, canonical tags, duplicate content, status codes (200, 301, 404, 5xx).
Rendering. Whether content and links appear in the HTML or depend on JavaScript (see JavaScript SEO).
Site structure. Logical URLs, sensible depth (important pages within a few clicks of the homepage), breadcrumbs, pagination, faceted navigation.
Speed and page experience. Server response time, page weight, Core Web Vitals, mobile usability.
Security. HTTPS, valid certificates, no mixed content, security headers.
Structured data. Schema markup that helps search engines understand entities and enables rich results.
International and multi-location setups. Hreflang, location pages.
AI crawler access. Whether AI search bots can reach the site, and whether a firewall is blocking them by accident.
Why it matters
Technical problems tend to be all-or-nothing. A single misplaced line in robots.txt, a noindex tag on a template, or a migration without redirects can remove hundreds of pages from Google overnight.
When Brightside Dental moved to a new website platform, the developer changed every URL from /services/teeth-whitening.html to /teeth-whitening/ without adding redirects. Within a month, rankings that took years to build had collapsed, and every backlink pointed at a 404. Setting up 301 redirects from each old URL to its new one recovered most of it over the following weeks. A pre-launch technical check would have avoided the loss entirely.
Where to start
- Confirm important pages are indexed (Search Console’s Page indexing report).
- Fix broken pages and links, and redirect old URLs properly.
- Make sure every page is on HTTPS, with one canonical version of the site.
- Check mobile usability and Core Web Vitals on your main templates.
- Make sure key content is in the HTML.
- Add basic structured data for your business and main page types.
Common mistakes
- Treating technical SEO as a one-off project instead of something to recheck after every redesign, migration or plugin change
- Chasing perfect speed scores while indexing problems go unfixed
- Launching redesigns without a redirect plan
How to check
A regular SEO audit is the backbone of technical SEO. RankThat’s Site Audit covers crawlability, indexing, links, speed, security, schema, mobile and AI readiness across 100+ checks, each with a plain-English explanation and fix.