SEO basics
What is technical SEO?
Technical SEO is the practice of making sure search engines can find, crawl, and index your website without friction. It is the foundation all other SEO work depends on — excellent content and off-page links provide no ranking value if Google cannot access or understand the page in the first place. According to Google's How Search Works documentation, crawling and indexing are the prerequisites for any page appearing in search results at all. Technical SEO covers your robots.txt and sitemap.xml files, your site's loading speed and Core Web Vitals scores, mobile-friendliness, structured data (schema) markup, canonical tags that prevent duplicate content, and the consistency of your internal link structure. Most technical issues are invisible to users but plainly visible to crawlers — which is why a technical audit is always the first step in any SEO engagement.
Crawlability: robots.txt and sitemaps
Before Google can rank a page, it must first find and crawl it. Two files control this process. The robots.txt file (located at the root of your domain) tells crawlers which pages they are allowed to access and which to skip. The sitemap.xml file lists every page on your site and its last modification date, giving Google a complete roadmap. Without a sitemap, new pages can take weeks to be discovered. With one, discovery is typically a matter of days. Google's documentation on robots.txt confirms that correctly configured crawl directives prevent Google from wasting its crawl budget on low-value pages and missing the ones that matter.
Core Web Vitals and page speed
Google uses Core Web Vitals as a ranking input — specifically three metrics: Largest Contentful Paint (LCP, how fast the main content loads), Interaction to Next Paint (INP, how quickly the page responds to user input), and Cumulative Layout Shift (CLS, how much the page moves around as it loads). Google's web.dev documentation on Core Web Vitals defines the targets: LCP under 2.5 seconds, INP under 200 milliseconds, CLS under 0.1. Pages that fail these thresholds are penalised in rankings compared to equivalent content on faster pages. The most common causes of poor scores are unoptimised images, render-blocking JavaScript, and web fonts that delay text display.
Structured data and schema markup
Structured data is code (typically JSON-LD) embedded in a page's HTML that tells Google precisely what the page contains — what type of business, what services are offered, what geographic areas are served, what questions are answered, and who authored the content. This data feeds rich results (star ratings, FAQ dropdowns, event cards in search results) and AI Overview citations. According to Google's structured data documentation, schema markup helps Google understand page content and enables enhanced search features. Every page on a well-built site should carry valid JSON-LD appropriate to its type — local business pages carry LocalBusiness and Service schema, FAQ pages carry FAQPage schema, and blog posts carry Article schema with a named author.
Canonical tags and duplicate content
A canonical tag (<link rel="canonical" href="..."> in the page head) tells Google which URL is the definitive version of a page. Without canonicals, pages accessible at multiple URLs (with and without trailing slashes, with and without query strings, on www and non-www subdomains) can be treated as duplicate content, diluting the ranking signals that should concentrate on one URL. Every page should carry a self-referencing canonical pointing to its own clean, preferred URL. This is a low-effort, high-impact technical fix that is easy to implement correctly from the start and costly to audit and repair across a large site later.