Technical SEO refers to optimisations that improve how search engines crawl, render, and index a website — as distinct from content quality (on-page SEO) or link acquisition (off-page SEO).
While content SEO focuses on what a page says, technical SEO focuses on whether search engines can access, understand, and efficiently process the page in the first place.
Core areas of technical SEO
Crawlability and indexation
- Robots.txt — Controls which pages search engine bots can crawl
- XML sitemap — Lists all important URLs to aid discovery
- Crawl budget — How many pages Googlebot crawls per day; important for large sites
- Canonical tags — Signals the preferred version of a URL to prevent duplicate content
Site speed and Core Web Vitals
Page speed is a confirmed ranking factor. Technical SEO includes optimising:
- Server response time (TTFB)
- Image compression and format (WebP)
- JavaScript and CSS delivery (minification, deferral, code splitting)
- CDN configuration
See Core Web Vitals for the specific metrics Google measures.
Mobile-friendliness
Google uses mobile-first indexing — it primarily uses the mobile version of your site for ranking. A non-mobile-friendly site will rank poorly regardless of content quality.
Structured data (schema markup)
JSON-LD markup helps Google understand the meaning of content: articles, FAQs, products, local businesses, and more. Rich results (star ratings, FAQ dropdowns in SERPs) require correct structured data.
HTTPS and security
Sites without HTTPS are flagged as insecure in Chrome and receive a minor ranking disadvantage. HTTPS is a baseline expectation, not a competitive advantage.
URL structure
Clean, descriptive URLs that reflect site hierarchy help both users and crawlers. Hyphens over underscores, lowercase, no unnecessary parameters.
Technical SEO vs. on-page SEO
| Technical SEO | On-Page SEO | |
|---|---|---|
| Focus | Infrastructure | Content |
| Examples | Crawlability, speed, schema | Title tags, headings, internal links |
| Who does it | Developers + SEO | Content + SEO |
Both are necessary. Technical issues can prevent even great content from ranking; poor content prevents even technically perfect sites from competing.