Technical SEO is the foundation everything else sits on. You can write exceptional content and build strong backlinks, but if Google can't crawl or index your pages, none of it matters. Technical SEO basics don't require a developer to understand - once you know what each component does and why it matters, you can audit your site intelligently and prioritize the fixes that move rankings. This guide covers every core technical SEO element in plain English.
What technical SEO is (and what it isn't)
Technical SEO covers optimizations to a website's infrastructure - the code, server configuration, and architecture - that help search engines crawl, index, and rank pages effectively. It's distinct from on-page SEO (content and keyword optimization) and off-page SEO (backlinks and citations).
Think of it this way: on-page SEO is what you say; technical SEO is whether Google can hear you say it. A site with perfect content but broken technical foundations is invisible to search engines. A site with clean technical SEO amplifies everything else you do.
The core technical SEO elements
1. Crawlability - can Google access your pages?
Before Google can rank your pages, its crawler (Googlebot) must be able to access them. Crawlability problems are severe - they silently prevent rankings entirely, with no error message visible to site visitors.
Common crawlability issues:
- Robots.txt blocking: Your
robots.txtfile tells search engines which pages to crawl. A misconfigured robots.txt can accidentally block your entire site from being crawled. Check yours atyourdomain.com/robots.txtand verify that key pages aren't disallowed. - Noindex tags: Pages with a
<meta name="robots" content="noindex">tag are excluded from Google's index. Sometimes set during site development and never removed. - Login-required pages: Pages behind a login that Googlebot can't access won't be indexed. If your service pages or key content requires login, they won't rank.
- Broken internal links: Links pointing to 404 pages waste crawl budget and signal poor site health.
How to check: Google Search Console's Coverage report shows which pages are indexed, which are excluded, and why. Review it monthly.
2. Indexation - has Google stored your pages?
Crawling and indexation are different. Google crawls a page to read it; indexation is when it stores that page in its database for ranking consideration. A page can be crawled but not indexed if Google determines it's low-quality, duplicate, or not worth including.
Common indexation issues:
- Duplicate content: Near-identical pages (www vs non-www, HTTP vs HTTPS, trailing slash vs no trailing slash) create duplicate content that confuses Google about which version to index.
- Thin content: Pages with minimal unique content may be crawled but not indexed. Google increasingly excludes low-value pages from its index.
- Missing canonical tags: Without canonical tags, Google must guess which version of a URL is the "official" one. Canonical tags remove the guesswork.
- Sitemap issues: A missing, outdated, or misconfigured XML sitemap slows Google's discovery of your pages - especially on new or recently updated sites.
How to check: In Google Search Console, search site:yourdomain.com to see approximately how many pages are indexed. The Coverage report shows pages excluded from the index and the specific reason.
3. HTTPS and site security
HTTPS (Hypertext Transfer Protocol Secure) encrypts data between your website and visitors. Google confirmed HTTPS as a ranking signal in 2014, and in 2026 it's table stakes - non-secure HTTP sites are flagged as "Not Secure" in browsers and actively penalized in rankings.
- Verify your SSL certificate is valid and not expired
- Ensure all pages load over HTTPS (not HTTP)
- Set up 301 redirects from all HTTP URLs to their HTTPS equivalents
- Ensure your canonical tags and sitemap use HTTPS URLs
How to check: Visit your site and look for the padlock icon in the browser address bar. Click it to see certificate details and expiry date.
4. Site speed and Core Web Vitals
Google uses Core Web Vitals as official ranking signals - three measurements of real-user page experience:
- LCP (Largest Contentful Paint): How fast the main content element loads. Target: under 2.5 seconds. The biggest culprits are large unoptimized images and slow server response times.
- INP (Interaction to Next Paint): How quickly the page responds to user input (clicks, taps, key presses). Target: under 200ms. Heavy JavaScript is the most common cause of poor INP.
- CLS (Cumulative Layout Shift): How much page elements shift around as the page loads. Target: under 0.1. Images without defined dimensions and late-loading ads are common causes.
Common speed issues and fixes:
- Unoptimized images: The #1 cause of slow sites. Compress every image and convert to WebP format. Use lazy loading for images below the fold.
- Render-blocking JavaScript: Scripts that load in the
<head>before page content block rendering. Move non-critical scripts to defer or async loading. - Slow hosting: Cheap shared hosting with slow server response times (TTFB over 600ms) handicaps every other speed optimization. A fast host is the foundation.
- No caching: Browser caching allows returning visitors to load your pages faster. Enable it through your hosting panel or a caching plugin.
How to check: Google PageSpeed Insights gives a score and specific fix recommendations for any URL. Google Search Console's Core Web Vitals report shows field data from real users.
5. Mobile-friendliness
Google uses mobile-first indexing - the mobile version of your site is what Google crawls and ranks, not the desktop version. If your site isn't mobile-friendly, it's not fully indexed.
- Use responsive design that adapts to any screen size
- Ensure text is readable without zooming
- Ensure tap targets (buttons, links) are at least 48px in size
- Avoid horizontal scrolling on mobile
- Don't use Flash or other non-mobile-compatible technologies
How to check: Google Search Console's Mobile Usability report flags specific mobile issues. Google's Mobile-Friendly Test lets you check any URL.
6. XML sitemap
An XML sitemap is a file that lists all the important pages on your site, helping Google discover and crawl them efficiently. It's especially important for new sites, sites with many pages, and sites where some pages aren't well-linked internally.
- Your sitemap should be at
yourdomain.com/sitemap.xml - Submit it to Google Search Console and Bing Webmaster Tools
- Include only indexable pages - don't list pages with noindex tags or pages you don't want ranked
- Keep it updated: new pages should appear in the sitemap promptly
7. Structured data (schema markup)
Schema markup is code added to your pages that tells Google exactly what your content means - not just what it says. It enables rich results in search (star ratings, FAQ boxes, breadcrumbs) and is increasingly important for AI search citation.
Key schema types for technical seo basics:
- LocalBusiness: Name, address, phone, hours, service area - critical for local businesses
- Article: For blog posts - author, publish date, headline
- FAQPage: Enables FAQ rich results and AI search citations
- BreadcrumbList: Shows your page hierarchy in search results
- WebSite: Enables sitelinks search box in branded searches
How to check: Google's Rich Results Test validates your schema markup and shows a preview of any rich results your page qualifies for.
8. URL structure and redirects
- Use clean, descriptive URLs:
/blog/technical-seo-basics/not/p?id=4291 - Use 301 redirects (permanent) when moving or deleting pages - never leave old URLs as 404s if they had inbound links or organic traffic
- Avoid redirect chains (A redirects to B redirects to C) - they waste crawl budget and dilute link equity
- Set a preferred domain (www vs non-www) and redirect all traffic to it consistently
The fastest technical SEO wins for most sites
If you're auditing a site for the first time, fix these in order:
- Verify HTTPS is active and all pages redirect from HTTP
- Check robots.txt isn't blocking important pages
- Submit your sitemap to Google Search Console
- Fix any Coverage errors shown in Search Console
- Compress all unoptimized images
- Add LocalBusiness schema to your homepage and contact page
- Fix any broken internal links
A free SEO audit covers the full technical health of your site and identifies which issues are actively suppressing your rankings. Our SEO service handles technical SEO as part of a complete London business optimization strategy.