What Is Technical SEO? A Plain English Explanation

Technical SEO is the work that makes sure a search engine can find, read, understand and keep your pages. Everything else you pay for sits on top of it. If a page cannot be crawled, no headline, no keyword research and no amount of link building will get it in front of a customer.

I have worked in search for thirteen years, and the most common gap I find on Australian business sites is not the writing or the links. It is the plumbing nobody looks at. Most owners have been told their site needs technical SEO and come away with no clearer idea of what that means, what it costs to ignore, or how to tell whether their current provider is doing it. This is the plain version.

What Is Technical SEO? The Plain Definition

Technical SEO is the set of changes made to a website's infrastructure, code and configuration so that search engines can access and index its content. It is not a tool, a plugin or a monthly report. It is a set of conditions that either exist on your site or do not.

What technical SEO is not

It is not keyword research, content writing, link acquisition or social media, and it is not a substitute for any of them. I have seen sites with perfect technical health and no traffic, because there was nothing worth ranking. The reverse is more common: strong content trapped behind a broken foundation.

Why it is the foundation of everything else

Every other channel assumes a working page. Ads send paid traffic to a slow page and lose the sale at the checkout. Email links land on a page that returns a 404 after a redesign. Content ranks for nothing because it was published under a canonical pointing at the wrong URL. Fix the foundation once and all of those channels get better at the same time.

The Seven Categories That Cover All of It

Every technical issue I have ever fixed falls into one of seven groups. When I audit a site, I walk these in order, because a later category is meaningless if an earlier one is broken.

Crawling: can Google find it

Robots.txt directives, sitemaps, internal links and the crawl paths that lead a bot to your pages.

Rendering: can Google see it

Whether your content exists in the HTML or only appears once JavaScript has run. This is the category that catches modern sites out.

Indexing: can Google keep it

Indexability, noindex tags, canonical selection and the difference between a page that is crawled and a page that is stored and eligible.

Canonicals and duplication

Which version of a URL is the one that counts, and whether your site is competing with itself across http, https, www, trailing slashes and filter parameters.

Site speed and Core Web Vitals

The three measured signals Google uses for page experience, and the specific assets that slow a page down.

Structured data

The markup that tells a search engine what a page is about, such as a service, an article, a business location or a set of questions and answers.

Security and stability

HTTPS, expired certificates, server errors and the uptime record that decides whether a crawler trusts your site enough to keep visiting.

Why Most Pages Get No Traffic At All

The scale of the problem is larger than most owners expect, and it is measured rather than estimated.

The scale of the problem across the open web

Ahrefs studied its own index and reported that "96.55% of all pages in our index get zero traffic from Google, and 1.94% get between one and ten monthly visits." Set that against the size of the web Google actually keeps: the HTTP Archive Web Almanac 2024 reports that "its index is only around 400 billion documents" against a web of vastly more pages than that.

What separates a crawled page from a ranked one

Being crawled is the entry requirement, not the outcome. A page has to be crawled, rendered, judged worth keeping and then selected for a query. Most pages fail before the last step, often at the first.

The Checks I Run On Every Australian Site

These four checks take about an hour on a small business site and they find something useful almost every time.

robots.txt and crawl directives

A stray disallow line can hide an entire section of a site while the pages still return 200 to a browser. It is not a rare fault. The same Web Almanac study found that "These audits showed that 8.43% of desktop pages and 7.40% of mobile pages failed the tool's check for valid robots.txt files", which is roughly one page in twelve.

Sitemaps and internal links

Check the sitemap lists only live, indexable URLs, and follow your own internal links to see how many clicks it takes to reach a money page. Anything three clicks deep on a small site is usually being under-crawled.

Status codes, redirects and chains

Every URL should return one clear status. A chain of three redirects from an old redesign wastes crawl budget and leaks authority. Redirect loops are worse and take traffic straight to an error page.

Mobile rendering and content parity

Compare what a phone sees with what a desktop sees. If the phone version drops a service description, a price or a suburb, that is the version most of your traffic is being judged on.

Core Web Vitals Without The Panic

Page speed matters, but not in the way most audit reports imply. Google's own guidance is narrower than the industry chatter around it.

The three metrics and their thresholds

Largest Contentful Paint measures how long the main content takes to appear, and Google's own documentation on LCP states that "sites should strive to have Largest Contentful Paint of 2.5 seconds or less". Interaction to Next Paint measures responsiveness, and Cumulative Layout Shift measures how much the page moves while it loads.

What to fix first when the score is red

Start with whatever loads first and blocks everything else: oversized hero images, fonts that block rendering, and third party scripts nobody has reviewed for two years. Those three fixes move the score more than any plugin will.

Technical SEO Audit: What It Should Include

What a proper crawl should extract

A real crawl reports status codes for every URL, canonical tags, indexability, title and heading duplication, redirect chains, orphan pages, broken internal links and page speed at template level. Template level matters, because one template fault usually affects hundreds of URLs at once.

Red flags in a cheap audit report

Be wary of a report that lists hundreds of pages with no priority order, flags missing alt text on decorative images as a critical issue, or recommends a plugin before it has checked whether your pages are indexed at all. A useful audit ends with the three or four things that matter this month and what each one costs you if you leave it.

If you want to see the checks written out, work through our technical SEO checklist against your own site, and note what breaks. A full SEO audit covers this and the rest: technical health, content, and the enquiry path.

How Often You Should Check This

The daily, monthly and yearly rhythm

Daily is uptime and server errors. Monthly is index coverage, sitemap health and a spot check on your top ten pages. Yearly is a full crawl, plus a review of anything you have not touched since the last one.

What to check after every site change

Any redesign, migration or plugin update should be followed by a check of robots.txt, canonicals, status codes and analytics tracking. If tracking needs to move, then before you migrate tracking, book the technical check as well, because a migration done in the wrong order costs you the history you need to judge whether the site is improving.

DIY Versus Hiring Someone

The checks an owner can run safely

You can read your own robots.txt, fetch a page and inspect its HTML, confirm your pages are indexed in Search Console, and look at mobile rendering. None of that requires a developer and all of it is worth understanding before you pay anyone.

The work that needs a developer

Server configuration, redirect rules in a server file, template level changes and anything touching checkout or forms should be done by someone who can back the site up first. Editing a robots file or a server config without a backup is the fastest way to take your own site offline. You can see how these fixes played out on real sites in the case studies I have documented, where the starting point was almost always a technical fault rather than a content problem.

Ten Technical Issues I See Constantly

After thirteen years and hundreds of audits, the same faults keep turning up. Three of them cause most of the damage.

Accidental noindex and robots blocks

A staging site is launched with a noindex tag still in the template, or a developer blocks a folder during a test and never removes the rule. The site looks fine in every browser and is invisible in search.

Canonicals pointing at the wrong URL

A template that outputs the same canonical on every page tells Google that all your pages are copies of one page. I have watched a 400 page site collapse to a single indexed URL this way.

Redirect chains from old redesigns

Every redesign adds another hop unless the rules are consolidated. After four years you can have a chain of five redirects between an old link and a live page, which is slow for users and wasteful for crawlers.

If you find one of those three faults on your site, fix it before you commission anything new. A broken canonical or an accidental noindex makes every other marketing dollar work harder for nothing.

Technical SEO FAQ

What is technical SEO in one sentence?

It is the work of making sure search engines can find, read, understand and keep your pages, so the content and links you have spent money on actually get a chance to rank.

How is technical SEO different from normal SEO?

Normal SEO decides what you say and who you say it to. Technical SEO makes sure the message is reachable. A site with excellent content and no indexing is a shop with the lights off and the door locked.

Do I need technical SEO if my site is small?

Yes, and it is usually faster to fix. A small site has fewer templates, so one correction often fixes hundreds of URLs at once. The checks above take an afternoon on most small business sites.

What is a good LCP score?

Google's own guidance is that sites should aim for a Largest Contentful Paint of 2.5 seconds or less, measured at the 75th percentile of page loads across mobile and desktop.

How do I know if my pages are indexed?

Search for a full page URL after the "site:" operator, and check the Pages report in Google Search Console. A page that returns 200 and looks fine can still be excluded, and that is the case worth investigating.

Can I break my site doing technical SEO myself?

You can, which is why the checklist marks the safe checks separately from the work that needs a developer. Editing robots.txt or a server config file without a recent backup is the most common way owners take a site offline by accident.