Technical SEO Guide

Technical SEO: The Foundation That Makes Everything Else Work

Great content and strong backlinks cannot compensate for a site Googlebot cannot crawl. Technical SEO is the multiplier for everything else. Get it right and every other investment in SEO performs better.

Core Web Vitals in 2025

Core Web Vitals became a confirmed ranking signal in 2021. In 2024, INP replaced FID as the interactivity metric. These are the three signals Google measures in the field (real user data) and weights in the page experience ranking component.

LCP
Largest Contentful PaintTarget: <2.5s
MeasuresHow long the largest visible element (usually a hero image or heading) takes to load.
CausesUnoptimised hero images, slow server response, render-blocking CSS/JS, no CDN.
FixPreload the LCP image with <link rel="preload">, serve WebP at correct dimensions, move to a CDN, defer non-critical CSS.
INP
Interaction to Next PaintTarget: <200ms
MeasuresResponsiveness — how quickly the page responds to user interactions across the full visit.
CausesHeavy JavaScript on the main thread, third-party scripts, unoptimised event handlers.
FixBreak up long tasks with scheduler.yield(), defer third-party scripts, reduce main thread blocking.
CLS
Cumulative Layout ShiftTarget: <0.1
MeasuresVisual stability — how much page elements move unexpectedly as content loads.
CausesImages without width/height attributes, ads injected above content, late-loading web fonts.
FixAdd explicit width and height to all images and embeds. Use font-display: optional or swap with a size-adjusted fallback.

Crawlability: letting Google in

Crawlability is binary: either Googlebot can reach your pages or it cannot. These are the four checks that matter most.

robots.txtShould allow Googlebot on all pages you want indexed. The most common mistake: a development-era "Disallow: /" that was never removed. Check yourdomain.com/robots.txt in browser and test it in GSC.
XML sitemapSubmit to GSC. Should include only canonical, indexable URLs. Exclude noindex pages, paginated URLs (unless canonical), and redirected URLs. Keep it under 50,000 URLs per file.
Crawl budgetRelevant for sites with 10,000+ pages. Crawl budget is how many pages Googlebot crawls per day. Wastes include redirect chains, duplicate content, soft 404s, and URL parameters generating infinite variations.
Internal link depthEvery page should be reachable within 3 clicks from the homepage. Pages buried deeper than 5 clicks are unlikely to be crawled frequently. Check with Screaming Frog's crawl depth report.

Indexability: getting into Google's index

Crawlable does not mean indexed. Google may crawl a page but choose not to include it in the index. The most common indexability issues:

Issue
Fix
noindex tag on page you want ranked
Remove the meta robots noindex tag or x-robots-tag header. Check GSC Coverage for "Excluded by noindex tag" pages.
Canonical pointing to wrong URL
Canonical should point to the preferred version of each page. Self-referencing canonicals are fine. Canonicals pointing to a different domain or incorrect URL confuse Google.
Thin content duplicate pages
Consolidate thin variations. Use canonical to point duplicates to the main version. Delete and 301-redirect if no unique value exists.
Soft 404s
Pages that return 200 status but contain "not found" or empty content. Google stops indexing these. Return a proper 404 or 410 status, or add meaningful content.

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Schema markup: which types matter most

Schema markup does not directly improve rankings but unlocks rich results in SERPs — the visual enhancements that increase click-through rate from the same ranking position.

ArticleBlog posts, news articles. Enables Google to understand author, publish date, and headline for rich results.
FAQPages with question-and-answer content. Can trigger FAQ rich results in SERPs — significant CTR boost for informational queries.
ProductE-commerce product pages. Enables price, availability, and review stars in search results.
LocalBusinessLocation-based businesses. Signals NAP data to Google and supports Knowledge Panel.
BreadcrumbListSite navigation hierarchy. Shows breadcrumb path in SERPs, improving CTR and helping Google understand site structure.

Frequently asked questions

How often should you do a technical SEO audit?

A full technical audit quarterly, with a lighter crawl-and-index check monthly. Any time you make significant changes — CMS migration, site redesign, URL restructure, moving from HTTP to HTTPS — audit immediately after. Technical issues introduced by a redesign can tank rankings within weeks if not caught. Set up GSC alerts for crawl errors so you have a permanent early warning system.

What's the most common technical SEO error?

By volume: missing or duplicate title tags. By impact: accidental noindex or robots.txt blocks on key pages. The latter is catastrophic and easy to miss — a single robots.txt line can deindex your entire site. The most common way it happens: a developer copies production config from a staging environment that had crawling blocked. Check GSC Coverage report after every deployment.

Does site speed really affect rankings?

Yes, but not as a direct ranking factor in the way links are. Site speed affects rankings through Core Web Vitals (a confirmed ranking signal since 2021), user behaviour signals (high bounce rate on slow pages), and crawl budget (slow sites get crawled less frequently). The bigger effect is often indirect: a 1-second improvement in load time can increase conversion rate by 7%, which improves revenue even if the ranking uplift is modest.

What is structured data and does it help rankings?

Structured data (schema markup) is machine-readable code that helps Google understand what your content is about — not just the words, but the entity types (person, product, event, FAQ). It does not directly improve rankings, but it unlocks rich results in SERPs (star ratings, FAQ dropdowns, event details) that significantly increase CTR. Higher CTR from the same ranking position = more traffic without needing to rank higher.

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