SEO Basics: How Search Works and What SEO Really Means

SEO basics start with one idea: search engine optimisation means helping search engines find, understand and show your pages to people searching for what you offer. Google describes its search in three stages (crawling, indexing and serving), and SEO is the work of making your pages succeed at each one. This guide explains how Google Search works, the three parts of SEO, what Google says it does and doesn’t do, and how to tell whether your SEO is working, all from Google’s own Search Central documentation, checked on 12 October 2026.

Ready for the practical steps? Our on-page SEO checklist covers each page, and the WordPress SEO tutorial shows the settings on WordPress. This page is the foundation they build on.

What SEO is, and what it isn’t

SEO is about earning free (organic) visits from search engines by making useful pages that are easy for them to read. It’s different from search ads, which you pay for. Google is explicit on this: it doesn’t accept payment to crawl a site more often or rank it higher, and its Search Essentials say it doesn’t cost any money to appear in Google’s results, “no matter what anyone tries to tell you”. It also says it doesn’t guarantee that it will crawl, index or show any page, even one that follows all its guidelines.

So SEO isn’t a trick or a fee. It’s making sure the right pages exist, can be found, and are the best answer to what people search for.

How Google Search works

Stage 1: Crawling

There’s no central list of all web pages, so Google constantly looks for new and updated ones. Google calls this “URL discovery”. Some pages it already knows; others it finds by following links from known pages (for example, a category page linking to a new post); others come from sitemaps you submit. Its crawler, Googlebot, then downloads the page and renders it, running JavaScript with a recent version of Chrome, much as your browser does.

Google also explains that Googlebot doesn’t crawl every page it discovers and tries not to crawl a site too fast; server errors such as HTTP 500 tell it to slow down.

Stage 2: Indexing

Next, Google tries to understand what the page is about, analysing the text, key tags such as the <title> and image alt attributes, images and videos. It groups pages with similar content and picks one as the canonical, the version that may appear in results. It also gathers signals such as the page’s language, the country it’s relevant to and its usability. Indexing isn’t guaranteed: Google lists low-quality content, rules that block indexing and hard-to-index designs among common reasons pages are left out.

Stage 3: Serving results

When someone searches, Google looks through its index for matching pages and returns those it believes are the highest quality and most relevant. Google says relevance is determined by hundreds of factors, which can include the searcher’s location, language and device. Its example: a search for “bicycle repair shops” shows different results in Paris than in Hong Kong. The features on the results page change with the search too, such as local results for one query and images for another.

The three parts of SEO

Technical SEO: can Google reach and read your pages?

This covers everything that lets crawling and indexing work: a server that responds reliably, no accidental blocks in robots.txt or noindex tags, a sitemap, readable URLs, and pages that load quickly and work well on phones. Google’s Search Essentials note that most sites pass the bare-minimum technical requirements without realising it, so for a typical blog this part is mostly about avoiding mistakes.

On-page SEO: does each page answer the search?

This is the content itself and how it’s presented: matching what the searcher wants, a clear title and description, helpful headings, images with alt text, and links to related pages. Google’s helpful-content guidance asks whether a page offers original information or analysis and a complete answer, which is why this part matters most. Our keyword research guide explains how to choose what each page should target.

Off-page SEO: do others vouch for you?

Links from other sites help Google discover your pages and are one of the signals it uses. Google’s starter guide is careful to note that PageRank, its link-based algorithm, is just one of many signals. Earn links with content worth citing rather than buying or swapping them; our guide to the risks of backlink exchanges explains why.

What Google rewards: who, how and why

Google suggests judging your content by three questions, “Who, How, and Why”, as a way to stay in line with what its systems seek to reward.

• Who created it? Google encourages accurate authorship information, such as bylines that lead to more about the author, and warns that fabricated author profiles (made-up names, AI-generated headshots, false credentials) are deceptive and a sign of a low-quality page.
• How was it created? Readers trust content more when they can see how it was made. For product reviews, Google mentions explaining how many products were tested, the results and how the tests were run, with evidence such as photos.
• Why was it created? Google calls this perhaps the most important question. Content made primarily to help people aligns with what its core ranking systems reward; content made mainly to attract search visits doesn’t. Using automation, including AI, mainly to manipulate rankings breaks its spam policies.

For beginners, this is the heart of SEO: technical settings help Google read your pages, but the pages that rank long term are the ones written for people, by someone who knows the subject.

Why a page doesn’t show up in Google

Google’s own guide lists the usual reasons at each stage. Pages may not be crawled because of server or network problems, robots.txt rules, or because they’re behind a login. They may not be indexed because the content is low quality, a robots rule blocks indexing, or the design makes them hard to index. And a page can be indexed but still not shown, because it isn’t relevant to the searches people make, its quality is low, or a robots rule prevents serving.

A quick first check, from Google’s starter guide: search site:yourdomain.com. If you see your pages, Google has found and indexed at least some of them.

Search engines beyond Google

This guide uses Google’s documentation because Google explains its process in the most detail, but the same basics apply elsewhere. Other search engines, such as Bing, also crawl the web, index what they find and rank pages for relevance, so a page that’s easy to crawl, clearly written and genuinely useful tends to do well across all of them. Verify your site in Bing Webmaster Tools as well as Search Console, submit the same sitemap, and you cover most of the rest. Google’s own guide to its AI features says the usual SEO best practices apply to AI Overviews too, with no special requirements.

How long SEO takes

Google’s starter guide says some changes may take effect in a few hours and others could take several months, and suggests waiting a few weeks before judging whether a change helped. Not every change will make a noticeable difference. For a new site, building enough useful content and earning the first links usually takes months; plan for that rather than expecting results in days.

How to measure your SEO

• Google Search Console (free) shows which searches show your pages, how often people click, which pages are indexed and any problems Google finds.
• Your analytics, such as Google Analytics, shows how many visitors arrive from search and what they do next.
• Rank tracking shows where key pages sit for chosen keywords over time; our guide to rank tracking tools compares options.

Look at trends over weeks and months, not day-to-day changes, and compare the same period year on year for seasonal topics.

SEO terms you’ll meet

• Organic results: the unpaid search results, as opposed to ads.
• SERP: the search engine results page, everything shown for one search.
• Crawler (Googlebot): the program that discovers and downloads pages.
• Index: Google’s database of the pages it has processed.
• Canonical: the version of similar pages Google picks to show.
• Sitemap: a list of your pages you can submit to help Google find them.
• Impressions and clicks: how often your pages appear in results, and how often people click them, as reported in Search Console.
• Click-through rate (CTR): clicks divided by impressions.
• Backlink: a link from another site to yours.
• Search intent: what the searcher actually wants to do or know.

SEO basics: your first steps

1. Verify your site in Google Search Console and submit a sitemap.
2. Check that important pages aren’t blocked from indexing.
3. Pick one clear topic and search intent for each page.
4. Write the best answer you can, then run the on-page SEO checklist on it.
5. Link new pages from related older ones so Google finds them.
6. Review Search Console every few weeks and improve what’s close to ranking.