How does SEO work?
October 15, 20264 min read
SEO works by helping search engines crawl, index and rank your pages for the right searches. Here's what happens at each stage and what you can influence.
Quick answer
SEO works by making it easier for a search engine to do three things with your pages: find them, understand them, and decide they're a good answer to a particular search. You can't control the final ranking, but you can influence each of those steps, and problems at any one of them can keep a good page out of the results.
Step one: Google has to find the page
There's no central list of every web page. Google discovers pages mainly by following links from pages it already knows, and by reading sitemaps, which are files that list the pages a site wants found. Google calls this crawling, and the software that does it is called Googlebot.
Most problems at this stage are about links and access. If a new service page isn't linked from anywhere on your site, Google may never come across it; a link from your homepage or main menu usually fixes that. A sitemap submitted through Google Search Console gives Google a direct list of the pages you care about, which helps most on new or large sites, though it doesn't guarantee they'll be crawled. And a file called robots.txt can tell crawlers to stay away from parts of a site. That's useful, but a single wrong line in it can hide an entire site.
Step two: Google has to understand and store it
After crawling a page, Google analyses its text, images and other content, works out what it's about, and decides whether to store it in its index, the huge database it draws results from. Google states that it doesn't guarantee it will index every page it crawls.
Here the page itself does most of the work:
- Clear, specific content. A page that plainly explains one thing is easier to classify than a page that tries to cover everything.
- Honest titles and headings. The title tag is often what Google shows as the clickable headline in results, so it should describe the page and be short enough to show in full (why title length matters). Headings break the page into sections a reader, and a search engine, can follow.
- Text that isn't trapped. Important details like prices or opening hours should be written as text, not only shown inside an image.
- One version of each page. If the same content appears at several web addresses, Google has to guess which one to show. A canonical tag tells it which version is the main one.
Step three: Google decides what to show
When someone searches, Google looks through its index for matching pages and decides which to show first. It doesn't publish a full list of signals. Its documentation says relevance is decided by hundreds of factors, which can include the searcher's location, language and device.
This is what people usually mean by "ranking," and it's the step you control least. The biggest lever is matching what the searcher actually wants. Someone searching "how to fix a squeaky door" wants steps, probably on a phone. Someone searching "door repair near me" wants a business, its location and a way to contact it. Same topic, very different pages.
How the page behaves matters too. Google measures loading speed, responsiveness and visual stability with a set of metrics it calls Core Web Vitals, so a page that loads slowly or jumps around as it loads starts at a disadvantage. Beyond your own site, links from other relevant sites have long been one of the signals Google uses, though it describes them as one signal among many.
A quick worked example
Say you run a small landscaping company and want to be found for "patio installation" in your city.
You'd start by checking that your patio page is indexed, perhaps using the URL Inspection tool in Search Console. If it isn't, you'd look for the reason: is it linked from your menu? Is it blocked? Is it nearly identical to another page?
Next, you'd read the page as a customer would. Does the title mention patios and the city? Does the text describe the materials you use, the areas you cover, and roughly how a project runs? Are there photos of real jobs with useful descriptions?
Finally, you'd look outward: is your business listed with the same name, address and phone number on your Google Business Profile and in local directories? Have local suppliers or partners got a reason to link to you?
What SEO can't do
SEO can't force Google to rank a page, and anyone promising a guaranteed top position is overselling. Google's own advice for hiring an SEO is to walk away from anyone who makes that guarantee. Results also take time; Google suggests waiting a few weeks before judging a change, and some changes take months to show.
What SEO can do is remove the obstacles that keep good pages hidden, and make sure that when your page is the right answer, Google can tell.